This document summarizes key points from a Physics 121 lecture on magnetic fields and currents. It discusses how magnetic fields are created by currents and how to calculate magnetic fields using the Biot-Savart law and Ampere's law. Examples are provided for calculating the magnetic field from a long straight wire, a circular loop, and a solenoid. The relationships between current, magnetic field, and force are also summarized.
This document provides a summary of a lecture on magnetic fields and currents. Some key points include:
1) Magnetic fields are created by moving electric charges such as electric currents. The magnetic field exerts a force on moving charges that is perpendicular to both the magnetic field and the charge's velocity.
2) Currents in wires produce magnetic fields according to the Biot-Savart law. Solenoids and toroids can be used to produce nearly uniform magnetic fields within their centers.
3) Ampere's law can be used to relate the line integral of magnetic field around a closed loop to the electric current enclosed by the loop, similar to how Gauss' law relates electric field flux to enclosed charge.
1. The document discusses Faraday's law of induction and induced electric fields. It summarizes that changing magnetic flux induces an electromotive force (emf) in a conductor.
2. Faraday's law states that the magnitude of induced emf is equal to the rate of change of magnetic flux through a conductor. A changing magnetic field also induces an electric field in space.
3. The document provides equations for calculating induced emf and electric fields. It also discusses Lenz's law, which describes the direction of induced current to oppose the change in magnetic flux that causes it.
This document discusses the Biot-Savart law and its use in calculating magnetic fields. It begins by describing Biot and Savart's experimental observations which led to the mathematical expression of the Biot-Savart law. It then provides examples of using the law to calculate the magnetic field of a circular current loop and an ideal solenoid. For the solenoid, Ampere's law is used to derive an expression showing the interior magnetic field is directly proportional to the current and number of turns per unit length.
The document discusses magnetic fields created by electric currents. It explains that:
- A current-carrying wire creates a circular magnetic field around it, and the strength of the field decreases with distance from the wire.
- A flat coil and solenoid also produce magnetic fields, with field lines circling the coil anti-clockwise on one side and clockwise on the other. The field is strongest at the center of a solenoid.
- Current-carrying conductors experience forces in magnetic fields due to the interaction between the fields. Fleming's left-hand rule can be used to determine the direction of these forces.
The document discusses sources of magnetic fields, including the Biot-Savart law which describes the magnetic field from a current-carrying wire. It provides an example of calculating the magnetic field from a long straight wire using the Biot-Savart law. It also discusses the magnetic force between two parallel current-carrying wires and the magnetic field from a circular current loop. Ampere's law relates the line integral of the magnetic field around a closed loop to the current passing through the loop. The document concludes by discussing magnetic materials and their effect on applied magnetic fields.
- The document discusses magnetic fields created by electric currents. It covers the magnetic field of a moving point charge, the Biot-Savart law for calculating the magnetic field from a current-carrying wire, and an example calculation of the magnetic field from a long straight wire.
- The right hand rule is introduced for determining the direction of magnetic fields.
- Maxwell's equations for static magnetic fields in integral and differential form are presented.
- The document discusses magnetic fields created by electric currents. It covers the magnetic field of a moving point charge, the Biot-Savart law for calculating the magnetic field from a current-carrying wire, and an example calculation of the magnetic field from a long straight wire.
- The right hand rule is introduced for determining the direction of magnetic fields.
- Maxwell's equations for static magnetic fields in integral and differential form are presented.
This document provides a summary of a lecture on magnetic fields and currents. Some key points include:
1) Magnetic fields are created by moving electric charges such as electric currents. The magnetic field exerts a force on moving charges that is perpendicular to both the magnetic field and the charge's velocity.
2) Currents in wires produce magnetic fields according to the Biot-Savart law. Solenoids and toroids can be used to produce nearly uniform magnetic fields within their centers.
3) Ampere's law can be used to relate the line integral of magnetic field around a closed loop to the electric current enclosed by the loop, similar to how Gauss' law relates electric field flux to enclosed charge.
1. The document discusses Faraday's law of induction and induced electric fields. It summarizes that changing magnetic flux induces an electromotive force (emf) in a conductor.
2. Faraday's law states that the magnitude of induced emf is equal to the rate of change of magnetic flux through a conductor. A changing magnetic field also induces an electric field in space.
3. The document provides equations for calculating induced emf and electric fields. It also discusses Lenz's law, which describes the direction of induced current to oppose the change in magnetic flux that causes it.
This document discusses the Biot-Savart law and its use in calculating magnetic fields. It begins by describing Biot and Savart's experimental observations which led to the mathematical expression of the Biot-Savart law. It then provides examples of using the law to calculate the magnetic field of a circular current loop and an ideal solenoid. For the solenoid, Ampere's law is used to derive an expression showing the interior magnetic field is directly proportional to the current and number of turns per unit length.
The document discusses magnetic fields created by electric currents. It explains that:
- A current-carrying wire creates a circular magnetic field around it, and the strength of the field decreases with distance from the wire.
- A flat coil and solenoid also produce magnetic fields, with field lines circling the coil anti-clockwise on one side and clockwise on the other. The field is strongest at the center of a solenoid.
- Current-carrying conductors experience forces in magnetic fields due to the interaction between the fields. Fleming's left-hand rule can be used to determine the direction of these forces.
The document discusses sources of magnetic fields, including the Biot-Savart law which describes the magnetic field from a current-carrying wire. It provides an example of calculating the magnetic field from a long straight wire using the Biot-Savart law. It also discusses the magnetic force between two parallel current-carrying wires and the magnetic field from a circular current loop. Ampere's law relates the line integral of the magnetic field around a closed loop to the current passing through the loop. The document concludes by discussing magnetic materials and their effect on applied magnetic fields.
- The document discusses magnetic fields created by electric currents. It covers the magnetic field of a moving point charge, the Biot-Savart law for calculating the magnetic field from a current-carrying wire, and an example calculation of the magnetic field from a long straight wire.
- The right hand rule is introduced for determining the direction of magnetic fields.
- Maxwell's equations for static magnetic fields in integral and differential form are presented.
- The document discusses magnetic fields created by electric currents. It covers the magnetic field of a moving point charge, the Biot-Savart law for calculating the magnetic field from a current-carrying wire, and an example calculation of the magnetic field from a long straight wire.
- The right hand rule is introduced for determining the direction of magnetic fields.
- Maxwell's equations for static magnetic fields in integral and differential form are presented.
1) The Biot-Savart law describes the magnetic field generated by a current-carrying conductor. It states that the magnetic field is proportional to the current and inversely proportional to the distance from the current element.
2) The direction of the magnetic field generated by a current element is perpendicular to both the current element and the line from the current element to the point where the magnetic field is calculated.
3) Examples of applying the Biot-Savart law include calculating the magnetic field generated by a circular loop of wire and along the axis of a solenoid. The magnetic fields add linearly for multiple current elements.
This document summarizes key concepts from a chapter on magnetic fields. It discusses the magnetic field created by a current-carrying wire, which is perpendicular to the wire. It also describes how a current loop acts as a magnet, with a magnetic dipole moment proportional to the current and area of the loop. Additionally, it covers Ampere's law relating the line integral of magnetic field around a closed loop to the current passing through the enclosed area.
Magnetic Effects Of Current Class 12 Part-1Self-employed
The document discusses the magnetic effects of electric current, including:
1) Oersted's experiment showing a current-carrying wire deflects a magnetic needle.
2) Rules for determining the direction of magnetic fields, including Ampere's swimming rule and Maxwell's corkscrew rule.
3) Biot-Savart's law, which describes the magnetic field created by a current-carrying element as proportional to the current and inversely proportional to the distance.
1) Ampere's circuital law states that the line integral of the magnetic field B around any closed path is equal to the permeability of free space times the total current passing through the enclosed area.
2) The law can be used to calculate magnetic fields due to various current carrying conductors like long straight wires, solenoids, and toroids.
3) For a long straight wire, the magnetic field at a distance r is given by B=μ0I/2πr. For a solenoid, the magnetic field inside is uniform and given by B=μ0nI, where n is number of turns per unit length. For a toroid, the magnetic field within is also
The document discusses the magnetic effects of electric current, including Oersted's experiment showing a magnetic needle deflecting near a current-carrying wire. It introduces several rules for determining the direction of magnetic fields, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right-hand thumb rule. Biot-Savart's law is presented relating the magnetic field to the current, length element, distance, and angle. Magnetic field calculations are shown for a straight wire, circular loop, and solenoid carrying current.
The document discusses the magnetic effects of electric current, including:
1) Oersted's experiment showing a current-carrying wire deflects a magnetic needle.
2) Rules for determining the direction of magnetic fields, including Ampere's swimming rule and Maxwell's corkscrew rule.
3) Biot-Savart's law relating the magnetic field to the current, length element, and distance.
4) Expressions for the magnetic field of an infinitely long straight wire, circular loop, and solenoid.
1) Magnets attract iron-containing materials due to their magnetic properties which arise from the alignment of electron spins in their atoms.
2) Øersted discovered that electric currents produce magnetic fields according to the right-hand rule. Biot-Savart's law describes how the magnetic field is produced by a current-carrying conductor.
3) Biot-Savart's law states that the magnetic field produced by a current element is directly proportional to the current and length of the element and inversely proportional to the distance from the element. The direction of the magnetic field is perpendicular to both the current element and the line from the element to the point of interest.
The document discusses the magnetic effects of electric current. It begins by describing Oersted's experiment which showed a magnetic needle deflecting when placed near a current-carrying wire. It then provides rules for determining the direction of magnetic fields, including Ampere's swimming rule and the right hand thumb rule. Biot-Savart's law is introduced, stating the magnetic field is proportional to the current and inversely proportional to the distance squared. Magnetic field calculations are shown for a straight wire, circular loop, and solenoid carrying current.
- The document discusses electromagnetic induction and time-varying magnetic fields.
- If a magnetic field is changing with time, it will induce an electric field. The direction of the induced electric field is such that it opposes the change producing it.
- Lenz's law gives the direction of the induced current/electric field in terms of trying to oppose the change in magnetic flux that caused it.
The document discusses the magnetic effects of electric current. It describes Oersted's experiment which showed that a current-carrying wire deflects a nearby compass needle. It then provides rules for determining the direction of magnetic fields, including Ampere's swimming rule and the right hand thumb rule. Biot-Savart's law is introduced, relating the magnetic field to properties of the current. Magnetic field calculations are shown for a straight wire, circular loop, and solenoid carrying current.
1) The document summarizes a physics lecture on induction, electromagnetic oscillations, and LC circuits.
2) Key topics included Faraday's law of induction, Lenz's law, inductance, RL circuits, LC circuits, and deriving the oscillation frequency of LC circuits.
3) Damped oscillations in non-ideal LC circuits were also discussed, where resistance causes the amplitude of oscillations to decrease over time.
magnetic effect of current class 12th physics pptArpit Meena
1) Oersted's experiment showed that an electric current produces a magnetic field, as a compass needle was deflected when placed near a current-carrying wire.
2) There are several rules to determine the direction of magnetic fields, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right-hand thumb rule.
3) Biot-Savart's law quantitatively describes the magnetic field generated by a current-carrying conductor in terms of the current, length of conductor, and distance from the field point. It shows the field depends on the sine of the angle between the current and field point.
The document discusses magnetostatics and provides definitions and explanations of key concepts including magnetic field, magnetic flux, Biot-Savart law, Ampere's law, solenoids, ballistic galvanometers, and damping conditions. Specific topics covered include the magnetic field produced by steady currents, magnetic field lines, curl and divergence of magnetic fields, theory and operation of ballistic galvanometers, and current and charge sensitivity of galvanometers. Examples and derivations of equations for magnetic fields and forces on conductors in fields are also provided.
The document discusses the magnetic effects of electric current. It begins by explaining Oersted's experiment which showed that electric current produces a magnetic field. It then provides several rules for determining the direction of magnetic fields, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right hand thumb rule. Biot-Savart's law is introduced to quantify the magnetic field produced by a current-carrying element. Expressions are derived for the magnetic fields produced by an infinitely long straight wire, a circular loop, and a solenoid.
[L2 Sambhav] Electro magnetic induction.pdfSaptakPaul
1. The document provides information about various coaching institutes for JEE preparation with their prices and enrollment details.
2. Yalgaar Reloaded, Yoddha Reloaded and Udaan Plus are listed as options for JEE 2025 and 2024 batches with prices ranging from Rs. 12,824 to Rs. 26,999.
3. Dropper courses are also listed for JEE 2024 with prices starting from Rs. 13,299.
Ampere's Circuital Law states the relationship between the current and the magnetic field created by it. This law states that the integral of magnetic field density (B) along an imaginary closed path is equal to the product of current enclosed by the path and permeability of the medium.
1. Electric currents flowing in wires produce magnetic fields around the wires. The direction of the magnetic field can be determined using the right-hand grip rule.
2. A wire carrying a current experiences a force when placed in a magnetic field. The direction of this force can be determined using Fleming's left-hand rule. Charged particles also experience a force in a magnetic field.
3. Parallel wires with currents in the same direction attract, while parallel wires with currents in opposite directions repel. This is due to the interaction of the magnetic fields produced by each current.
This document discusses magnetic fields created by electric currents. It begins by introducing magnetic fields and magnets. It then explains that a current-carrying wire creates a circular magnetic field, as shown by iron filings. The direction of the field depends on the current direction. A flat coil and solenoid also produce magnetic fields, with the solenoid's field resembling that of a bar magnet. Current-carrying wires and charged particles experience forces in magnetic fields according to Fleming's left-hand rule. Parallel wires with the same/opposite currents attract/repel each other due to their magnetic fields. The ampere is defined based on the force between parallel current-carrying wires. Magnetic field strength B is directly
This document contains information about electricity and magnetism concepts including:
1. It defines key equations for electric potential, current, resistance, and force due to magnetic fields.
2. It discusses how moving charges experience forces in magnetic fields, and how this relates to phenomena like the aurora borealis and the operation of motors and generators.
3. It introduces concepts like induced currents and how changing magnetic fields can generate electric currents and voltages in conductors according to Lenz's law, which has applications in technologies like electric generators.
1) When an electric current flows through a wire, it produces a magnetic field around the wire. Oersted discovered this through an experiment where a magnetic needle deflected when placed near a current-carrying wire.
2) Several rules describe the direction of magnetic fields produced by currents, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right-hand thumb rule.
3) Biot-Savart's law quantitatively relates the magnetic field to the current, length, and position. It shows the field depends on the current and is inversely proportional to the distance from the wire.
1) The Biot-Savart law describes the magnetic field generated by a current-carrying conductor. It states that the magnetic field is proportional to the current and inversely proportional to the distance from the current element.
2) The direction of the magnetic field generated by a current element is perpendicular to both the current element and the line from the current element to the point where the magnetic field is calculated.
3) Examples of applying the Biot-Savart law include calculating the magnetic field generated by a circular loop of wire and along the axis of a solenoid. The magnetic fields add linearly for multiple current elements.
This document summarizes key concepts from a chapter on magnetic fields. It discusses the magnetic field created by a current-carrying wire, which is perpendicular to the wire. It also describes how a current loop acts as a magnet, with a magnetic dipole moment proportional to the current and area of the loop. Additionally, it covers Ampere's law relating the line integral of magnetic field around a closed loop to the current passing through the enclosed area.
Magnetic Effects Of Current Class 12 Part-1Self-employed
The document discusses the magnetic effects of electric current, including:
1) Oersted's experiment showing a current-carrying wire deflects a magnetic needle.
2) Rules for determining the direction of magnetic fields, including Ampere's swimming rule and Maxwell's corkscrew rule.
3) Biot-Savart's law, which describes the magnetic field created by a current-carrying element as proportional to the current and inversely proportional to the distance.
1) Ampere's circuital law states that the line integral of the magnetic field B around any closed path is equal to the permeability of free space times the total current passing through the enclosed area.
2) The law can be used to calculate magnetic fields due to various current carrying conductors like long straight wires, solenoids, and toroids.
3) For a long straight wire, the magnetic field at a distance r is given by B=μ0I/2πr. For a solenoid, the magnetic field inside is uniform and given by B=μ0nI, where n is number of turns per unit length. For a toroid, the magnetic field within is also
The document discusses the magnetic effects of electric current, including Oersted's experiment showing a magnetic needle deflecting near a current-carrying wire. It introduces several rules for determining the direction of magnetic fields, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right-hand thumb rule. Biot-Savart's law is presented relating the magnetic field to the current, length element, distance, and angle. Magnetic field calculations are shown for a straight wire, circular loop, and solenoid carrying current.
The document discusses the magnetic effects of electric current, including:
1) Oersted's experiment showing a current-carrying wire deflects a magnetic needle.
2) Rules for determining the direction of magnetic fields, including Ampere's swimming rule and Maxwell's corkscrew rule.
3) Biot-Savart's law relating the magnetic field to the current, length element, and distance.
4) Expressions for the magnetic field of an infinitely long straight wire, circular loop, and solenoid.
1) Magnets attract iron-containing materials due to their magnetic properties which arise from the alignment of electron spins in their atoms.
2) Øersted discovered that electric currents produce magnetic fields according to the right-hand rule. Biot-Savart's law describes how the magnetic field is produced by a current-carrying conductor.
3) Biot-Savart's law states that the magnetic field produced by a current element is directly proportional to the current and length of the element and inversely proportional to the distance from the element. The direction of the magnetic field is perpendicular to both the current element and the line from the element to the point of interest.
The document discusses the magnetic effects of electric current. It begins by describing Oersted's experiment which showed a magnetic needle deflecting when placed near a current-carrying wire. It then provides rules for determining the direction of magnetic fields, including Ampere's swimming rule and the right hand thumb rule. Biot-Savart's law is introduced, stating the magnetic field is proportional to the current and inversely proportional to the distance squared. Magnetic field calculations are shown for a straight wire, circular loop, and solenoid carrying current.
- The document discusses electromagnetic induction and time-varying magnetic fields.
- If a magnetic field is changing with time, it will induce an electric field. The direction of the induced electric field is such that it opposes the change producing it.
- Lenz's law gives the direction of the induced current/electric field in terms of trying to oppose the change in magnetic flux that caused it.
The document discusses the magnetic effects of electric current. It describes Oersted's experiment which showed that a current-carrying wire deflects a nearby compass needle. It then provides rules for determining the direction of magnetic fields, including Ampere's swimming rule and the right hand thumb rule. Biot-Savart's law is introduced, relating the magnetic field to properties of the current. Magnetic field calculations are shown for a straight wire, circular loop, and solenoid carrying current.
1) The document summarizes a physics lecture on induction, electromagnetic oscillations, and LC circuits.
2) Key topics included Faraday's law of induction, Lenz's law, inductance, RL circuits, LC circuits, and deriving the oscillation frequency of LC circuits.
3) Damped oscillations in non-ideal LC circuits were also discussed, where resistance causes the amplitude of oscillations to decrease over time.
magnetic effect of current class 12th physics pptArpit Meena
1) Oersted's experiment showed that an electric current produces a magnetic field, as a compass needle was deflected when placed near a current-carrying wire.
2) There are several rules to determine the direction of magnetic fields, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right-hand thumb rule.
3) Biot-Savart's law quantitatively describes the magnetic field generated by a current-carrying conductor in terms of the current, length of conductor, and distance from the field point. It shows the field depends on the sine of the angle between the current and field point.
The document discusses magnetostatics and provides definitions and explanations of key concepts including magnetic field, magnetic flux, Biot-Savart law, Ampere's law, solenoids, ballistic galvanometers, and damping conditions. Specific topics covered include the magnetic field produced by steady currents, magnetic field lines, curl and divergence of magnetic fields, theory and operation of ballistic galvanometers, and current and charge sensitivity of galvanometers. Examples and derivations of equations for magnetic fields and forces on conductors in fields are also provided.
The document discusses the magnetic effects of electric current. It begins by explaining Oersted's experiment which showed that electric current produces a magnetic field. It then provides several rules for determining the direction of magnetic fields, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right hand thumb rule. Biot-Savart's law is introduced to quantify the magnetic field produced by a current-carrying element. Expressions are derived for the magnetic fields produced by an infinitely long straight wire, a circular loop, and a solenoid.
[L2 Sambhav] Electro magnetic induction.pdfSaptakPaul
1. The document provides information about various coaching institutes for JEE preparation with their prices and enrollment details.
2. Yalgaar Reloaded, Yoddha Reloaded and Udaan Plus are listed as options for JEE 2025 and 2024 batches with prices ranging from Rs. 12,824 to Rs. 26,999.
3. Dropper courses are also listed for JEE 2024 with prices starting from Rs. 13,299.
Ampere's Circuital Law states the relationship between the current and the magnetic field created by it. This law states that the integral of magnetic field density (B) along an imaginary closed path is equal to the product of current enclosed by the path and permeability of the medium.
1. Electric currents flowing in wires produce magnetic fields around the wires. The direction of the magnetic field can be determined using the right-hand grip rule.
2. A wire carrying a current experiences a force when placed in a magnetic field. The direction of this force can be determined using Fleming's left-hand rule. Charged particles also experience a force in a magnetic field.
3. Parallel wires with currents in the same direction attract, while parallel wires with currents in opposite directions repel. This is due to the interaction of the magnetic fields produced by each current.
This document discusses magnetic fields created by electric currents. It begins by introducing magnetic fields and magnets. It then explains that a current-carrying wire creates a circular magnetic field, as shown by iron filings. The direction of the field depends on the current direction. A flat coil and solenoid also produce magnetic fields, with the solenoid's field resembling that of a bar magnet. Current-carrying wires and charged particles experience forces in magnetic fields according to Fleming's left-hand rule. Parallel wires with the same/opposite currents attract/repel each other due to their magnetic fields. The ampere is defined based on the force between parallel current-carrying wires. Magnetic field strength B is directly
This document contains information about electricity and magnetism concepts including:
1. It defines key equations for electric potential, current, resistance, and force due to magnetic fields.
2. It discusses how moving charges experience forces in magnetic fields, and how this relates to phenomena like the aurora borealis and the operation of motors and generators.
3. It introduces concepts like induced currents and how changing magnetic fields can generate electric currents and voltages in conductors according to Lenz's law, which has applications in technologies like electric generators.
1) When an electric current flows through a wire, it produces a magnetic field around the wire. Oersted discovered this through an experiment where a magnetic needle deflected when placed near a current-carrying wire.
2) Several rules describe the direction of magnetic fields produced by currents, including Ampere's swimming rule, Maxwell's corkscrew rule, and the right-hand thumb rule.
3) Biot-Savart's law quantitatively relates the magnetic field to the current, length, and position. It shows the field depends on the current and is inversely proportional to the distance from the wire.
This document discusses key aspects of organizational structure including division of labor, hierarchy of authority, span of control, line and staff positions, and decentralization. It examines tall vs flat hierarchies and appropriate span of control. It also differentiates between line and staff positions. The document contrasts mechanistic and organic designs, and looks at how size, complexity, differentiation, and other factors impact organizational effectiveness. Functional, product, market, and matrix structures are overviewed.
This document discusses understanding population risk to weather disasters in a changing climate. It provides two case studies: an extreme heat study in Texas that developed a system to assess current and future urban vulnerability to heat waves, and a flooding study in Colorado after the 2013 floods that found residents were surprised by the flooding extent and lack of adequate warnings. The document stresses that understanding risk and vulnerability at local scales can help with hazard mitigation and climate adaptation, and that even areas with high adaptive capacity contain "surprising" vulnerabilities that provide opportunities to learn and reduce disaster risk.
This document summarizes a methodology for conducting vulnerability assessments to evaluate risks from coastal hazards. It involves analyzing hazards, critical facilities, societal factors, economic impacts, environmental issues, and mitigation opportunities. GIS is used to map risk areas and intersecting factors. Metrics are established to prioritize hazards and vulnerabilities. The process identifies high-risk locations and populations to guide development of hazard mitigation strategies.
Biomass is a renewable energy source that includes plants and animals. It can be used to produce heat and electricity. Biomass energy refers to energy from recently living organic matter like plants and animals. There are several ways to convert biomass into energy, including direct combustion to produce heat, thermochemical conversion methods like pyrolysis and gasification, and biochemical conversion using microorganisms like anaerobic digestion and ethanol fermentation. While biomass energy has advantages like being renewable and reducing dependence on fossil fuels, it also has disadvantages like being less efficient than fossil fuels and requiring a lot of space for combustion.
The document discusses various biomass and biofuel technologies including:
1. Biomass is used today for industrial heat/steam, power generation, and transportation fuels like ethanol and biodiesel to modestly reduce fossil fuel use.
2. Technologies focus on sugar and thermochemical platforms to produce fuels, power, and chemicals from biomass at bio-refineries similar to petroleum refineries.
3. Biofuels discussed include biodiesel from oils, modified waste vegetable fat, ethanol diesel blends, and jatropha biodiesel.
This document discusses the Office of Basic Energy Sciences (BES) and its role in funding basic research related to energy production and use. It notes that BES provides over 40% of federal funding for physical sciences and operates scientific user facilities. The document then summarizes a workshop on basic research needs for the hydrogen economy, identifying key gaps in hydrogen production, storage, and fuel cells. It outlines BES's solicitation of proposals for basic research on hydrogen as part of the Department of Energy's hydrogen fuel initiative.
Sound or noise pollution can occur when there is excessive noise or unpleasant sounds that disrupt the natural environment. Common causes of noise pollution include traffic, aircraft, railways, construction activities, industrial machinery, and loud consumer products. Prolonged exposure to loud noises can negatively impact human and animal health by causing hearing loss, cardiovascular effects, sleep disturbances, and stress. To reduce noise pollution, soundproofing of machines, limits on vehicle horns, and enforcing silence zones are effective solutions, as well as increasing public awareness of the health risks of excessive noise.
This document discusses noise measurement and abatement. It defines sound and how it travels in waves. It explains how sound is measured in terms of pressure, frequency, intensity, bels, and decibels. It discusses common sources of noise pollution like transportation systems, and how noise affects human health. Solutions to noise problems include regulations, barriers, and selecting less noisy materials.
This document provides guidance on effective communication. It discusses the communication process and important concepts to consider, including the source, message, encoding, channel, decoding, receiver, feedback, and context. Good communication requires listening skills like focusing on the speaker, avoiding distractions, responding appropriately, asking clarifying questions, and understanding different perspectives. The document also discusses communicating respectfully by avoiding manipulation, double messages, or deception, and provides tips for resolving conflicts respectfully. Overall, the document emphasizes the importance of clear encoding and decoding of messages, active listening, and communicating respectfully.
We face significant health hazards from infectious diseases like flu, AIDS, tuberculosis, and malaria. There is also growing concern about chemicals that can cause cancer, birth defects, and disrupt human hormone and nervous systems. Bisphenol A is an example of an estrogen mimic found in many plastics and canned food linings that 93% of Americans have in their bodies. While scientists use animal testing and epidemiological studies to evaluate chemical toxicity, these methods have limitations. It is difficult to fully evaluate risks, so reducing chemical pollution and making informed lifestyle choices can help avoid health risks.
The document discusses different types of hazards and how they are classified. It defines a hazard as a process, phenomenon or human activity that can cause harm. Hazards are divided into several categories - natural, biological, environmental, geological, hydrometeorological, and technological. The document also discusses how hazards can be characterized by their magnitude, speed of onset, duration and area affected. It describes how hazard events are measured and analyzed, including through the use of historical data and computer-generated hazard event sets. The severity of hazard impacts can potentially be lessened through risk reduction strategies and actions.
This document discusses the importance of environmental education for sustainable development. It addresses several key issues: the current state of pollution and its effects like global warming; the types of pollution harming the environment; and natural disasters exacerbated by environmental damage. It emphasizes that sustainable development requires changes in attitudes through moral and ethical education to encourage environmentally-friendly behavior. While science and technology can help manage pollution, they cannot deliver sustainability alone. The document argues for hands-on environmental education that inspires interest in conservation issues. Curricula should incorporate moral philosophy and focus on reducing consumption. Proper management of resources like water is vital for environmental protection.
This document discusses photochemical smog, which is air pollution caused by chemical reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight. It focuses on Los Angeles as a case study, noting that the stable atmosphere, plenty of sunlight, and high traffic volume provide ideal conditions for photochemical smog formation. The chemical reactions that produce smog are described, and it is noted that weather conditions like high pressure systems can cause air stagnation and exacerbate smog levels. Emission control strategies California has implemented like catalytic converters and carpool lanes are also summarized.
Global warming is caused by greenhouse gases like carbon dioxide and methane that are released by human activities such as burning fossil fuels and deforestation. The average global temperature has already risen by 1°C in the past century and is projected to increase by over 1°C in the next 100 years if emissions continue rising. Some effects of climate change include rising sea levels from melting ice caps, more extreme weather, droughts, and loss of habitats. Individual actions like reducing waste, using less plastic, and buying locally grown food can help reduce greenhouse gas emissions and slow global warming.
This document discusses acids, bases, and salts. It explains that acids contain hydrogen ions and bases contain hydroxide ions. When an acid and base react, they form water and a salt through a neutralization reaction. Salts are formed when hydrogen ions in an acid are replaced by metal ions. There are different types of salts including normal salts, acid salts, and basic salts depending on the reaction that forms them. Salts have various uses such as in fertilizers, drying agents, medicines, and gunpowder.
This document provides an overview of solutions and solubility. It defines key terms like solute, solvent, solution, homogeneous mixture, heterogeneous mixture, concentration, saturation, and factors that affect solubility. It also discusses quantitative concepts such as molarity, percent by mass, and how to use stoichiometry to calculate amounts in solutions. Specifically, it explains how to calculate amounts of solutes and solvents needed using molarity, percent by mass, and mole ratios from balanced chemical equations.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
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physics121_lecture10.ppt
1. Physics 121: Electricity &
Magnetism – Lecture 10
Magnetic Fields & Currents
Dale E. Gary
Wenda Cao
NJIT Physics Department
2. November 7, 2007
Magnetic Field Review
Magnets only come in pairs of N
and S poles (no monopoles).
Magnetic field exerts a force on
moving charges (i.e. on currents).
The force is perpendicular to both
and the direction of motion (i.e.
must use cross product).
Because of this perpendicular
direction of force, a moving
charged particle in a uniform
magnetic field moves in a circle or
a spiral.
Because a moving charge is a
current, we can write the force in
terms of current, but since current
is not a vector, it leads to a kind of
messy way of writing the equation:
B
v
N S N S N S
B
v
q
FB
B
L
i
FB
3. November 7, 2007
N S
Magnetic Field Caused by Current
As you may know, it is possible to
make a magnet by winding wire in
a coil and running a current
through the wire.
From this and other experiments,
it can be seen that currents create
magnetic fields.
In fact, that is the only way that
magnetic fields are created.
If you zoom in to a permanent
magnet, you will find that it
contains a tremendous number of
atoms whose charges whiz around
to create a current.
The strength of the magnetic field
created by a current depends on
the current, and falls off as 1/r2.
N S
N S
N S
N S
N S
N S
N S
N S
N S
Electromagnetic
crane
4. November 7, 2007
Biot-Savart Law
The magnetic field due to an element
of current is
The magnetic field wraps in circles
around a wire. The direction of the
magnetic field is easy to find using the
right-hand rule.
Put the thumb of your right hand in
the direction of the current, and your
fingers curl in the direction of B.
3
0
2
0
4
ˆ
4 r
r
s
d
i
r
r
s
d
i
B
d
s
d
i
B
d
(out of
page)
Biot-Savart sounds like “Leo Bazaar”
light
of
speed
1
0
0
c
0 = permeability constant
exactly m/A
T
10
4 7
5. November 7, 2007
1. Which drawing below shows the correct
direction of the magnetic field, B, at the point P?
A. I.
B. II.
C. III.
D. IV.
Direction of Magnetic Field
I II III IV V
i i i
i
P P P P P
i
B B
B into
page
B into
page
B into
page
6. November 7, 2007
Just add up all of the contributions ds to
the current, keeping track of distance r.
Notice that . And r sin q = R,
So the integral becomes
The integral is a little tricky, but is
B due to a Long Straight Wire
2
2
s
R
r
3
0
4 r
r
s
d
i
B
d
0 0 3
0 sin
2
2
r
ds
r
i
dB
B
q
0 2
/
3
2
2
0
)
(
2 s
R
ds
R
i
B
R
i
s
R
s
R
i
B
2
2
0
0
2
2
0
R
i
B
2
0
B due to current in a long straight wire
7. November 7, 2007
Just add up all of the contributions ds to the
current, but now distance r=R is constant,
and .
Notice that . So the integral
becomes
For a complete loop, f = 2, so
B at Center of a Circular Arc of Wire
f
Rd
ds
3
0
4 r
r
s
d
i
B
d
f f
0 0
2
0
4
ds
R
i
dB
B
R
i
Rd
R
i
B
f
f
f
4
4
0
0
2
0
R
i
B
f
4
0
B due to current in circular arc
s
d
r
R
i
B
2
0
B at center of a full circle
8. November 7, 2007
How would you determine B in the center of
this loop of wire?
B for Lines and Arcs
70
°
90°
95
°
R
2R
3R
2.43 A
T
7.812
T
1
.
0
10
812
.
7
222
.
1
3
571
.
1
2
833
.
1
3
658
.
1
)
43
.
2
(
10
7
7
R
R
R
R
B
T
7.458
T
1
.
0
10
458
.
7
062
.
5
3
571
.
1
2
833
.
1
3
658
.
1
)
43
.
2
(
10
7
7
R
R
R
R
B
Say R = 10 cm, i = 2.43 A. Since 95° = 1.658
radians, 90° = 1.571 radians, 70° = 1.222
radians, 105° = 1.833 radians, we have
?
R
i
B
f
4
0
circular arc
(out of page)
(into page)
3
0
4 r
r
s
d
i
B
d
0
4 3
0
r
r
s
d
i
B
d
9. November 7, 2007
2. The three loops below have the same current.
Rank them in terms of magnitude of magnetic
field at the point shown, greatest first.
A. I, II, III.
B. II, I, III.
C. III, I, II.
D. III, II, I.
E. II, III, I.
Magnetic Field from Loops
I. II. III.
10. November 7, 2007
Recall that a wire carrying a current in a
magnetic field feels a force.
When there are two parallel wires carrying
current, the magnetic field from one causes a
force on the other.
When the currents are parallel, the two wires are
pulled together.
When the currents are anti-parallel, the two wires
are forced apart.
Force Between Two Parallel Currents
F
F
To calculate the force on b due to a, a
b
ba B
L
i
F
d
ia
2
0
R
i
B
2
0
d
L
i
i
F b
a
ba
2
0
Force between two parallel currents
B
L
i
FB
11. November 7, 2007
3. Which of the four situations below has the
greatest force to the right on the central
conductor?
A. I.
B. II.
C. III.
D. IV.
E. Cannot
determine.
Forces on Parallel Currents
I.
II.
III.
IV.
F greatest?
12. November 7, 2007
Ampere’s Law for magnetic fields is analogous to
Gauss’ Law for electric fields.
Draw an “amperian loop” around a system of
currents (like the two wires at right). The loop
can be any shape, but it must be closed.
Add up the component of along the loop, for
each element of length ds around this closed loop.
The value of this integral is proportional to the
current enclosed:
Ampere’s Law
i1 i2
B
enc
i
s
d
B 0
Ampere’s Law
13. November 7, 2007
Magnetic Field Outside a Long
Straight Wire with Current
We already used the Biot-Savart Law to show
that, for this case, .
Let’s show it again, using Ampere’s Law:
First, we are free to draw an Amperian loop of
any shape, but since we know that the
magnetic field goes in circles around a wire,
let’s choose a circular loop (of radius r).
Then B and ds are parallel, and B is constant
on the loop, so
And solving for B gives our earlier expression.
r
i
B
2
0
enc
i
s
d
B 0
Ampere’s Law
enc
i
r
B
s
d
B 0
2
r
i
B
2
0
14. November 7, 2007
Magnetic Field Inside a Long
Straight Wire with Current
Now we can even calculate B inside the wire.
Because the current is evenly distributed over
the cross-section of the wire, it must be
cylindrically symmetric.
So we again draw a circular Amperian loop
around the axis, of radius r < R.
The enclosed current is less than the total
current, because some is outside the
Amperian loop. The amount enclosed is
so
2
2
R
r
i
ienc
inside a straight wire
2
2
0
0
2
R
r
i
i
r
B
s
d
B enc
r
R
i
B
2
0
2
r
R
~1/r
~r
B
15. November 7, 2007
4. Rank the paths according to the value of
taken in the directions shown, most positive
first.
A. I, II, III, IV, V.
B. II, III, IV, I, V.
C. III, V, IV, II, I.
D. IV, V, III, II, I.
E. I, II, III, V, IV.
Fun With Amperian Loops
I.
II.
III.
IV.
V.
s
d
B
16. November 7, 2007
Solenoids
We saw earlier that a complete loop of
wire has a magnetic field at its center:
We can make the field stronger by
simply adding more loops. A many
turn coil of wire with current is called a
solenoid.
We can use Ampere’s Law to calculate
B inside the solenoid.
R
i
B
2
0
The field near the wires is still circular,
but farther away the fields blend into a
nearly constant field down the axis.
17. November 7, 2007
Solenoids
The actual field looks more like this:
Approximate that the field is constant inside
and zero outside (just like capacitor).
Characterize the windings in terms of
number of turns per unit length, n. Each
turn carries current i, so total current over
length h is inh.
Compare with electric field in a capacitor.
Like a capacitor, the field is uniform inside
(except near the ends), but the direction
of the field is different.
inh
i
Bh
s
d
B enc 0
0
only section that has non-zero
contribution
in
B 0
ideal solenoid
18. November 7, 2007
Toroids
Notice that the field of the solenoid sticks out
both ends, and spreads apart (weakens) at the
ends.
We can wrap our coil around like a doughnut, so
that it has no ends. This is called a toroid.
Now the field has no ends, but wraps uniformly
around in a circle.
What is B inside? We draw an Amperian loop
parallel to the field, with radius r. If the coil has
a total of N turns, then the Amperian loop
encloses current Ni.
iN
i
r
B
s
d
B enc 0
0
2
r
iN
B
2
0
inside toroid
19. November 7, 2007
Current-Carrying Coils
Last week we learned that a current-carrying
coil of wire acts like a small magnet, and we
defined the “dipole moment” (a vector) as
The direction is given by the right-hand rule.
Let your fingers curl around the loop in the
direction of i, and your thumb points in the
direction of B. Notice that the field lines of the
loop look just like they would if the loop were
replaced by a magnet.
We are able to calculate the field in the center
of such a loop, but what about other places.
In general, it is hard to calculate in places
where the symmetry is broken.
But what about along the z axis?
NiA
N is number of turns, A
is area of loop
20. November 7, 2007
B on Axis of Current-Carrying Coil
What is B at a point P on the z axis of the
current loop?
We use the Biot-Savart Law
to integrate around the current loop, noting
that the field is perpendicular to r.
By symmetry, the perpendicular part of B is
going to cancel around the loop, and only the
parallel part will survive.
3
0
4 r
r
s
d
i
B
d
cos
4
cos 2
0
||
r
ds
i
dB
dB
r
R
cos
2
2
z
R
r
R
z
R
ds
i
2
/
3
2
2
0
)
(
4
ds
z
R
iR
dB
B 2
/
3
2
2
0
||
)
(
4
2
/
3
2
2
2
0
)
(
2
)
(
z
R
iR
z
B
R
i
B
2
)
0
( 0
21. November 7, 2007
5. The magnetic field inside a Toroid is .
Using an Amperian loop, what is the expression
for the magnetic field outside?
A. Zero
B. The same, decreasing as 1/r.
C. The same, except decreasing as
1/r2.
D. The same, except increase as r.
E. Cannot determine.
B Outside a Toroid
r
iN
B
2
0
22. November 7, 2007
Summary
Calculate the B field due to a current using Biot-Savart Law
Permiability constant:
B due to long straight wire: circular arc: complete loop:
Force between two parallel currents
Another way to calculate B is using Ampere’s Law (integrate B around
closed Amperian loops):
B inside a long straight wire: a solenoid: a torus:
B on axis of current-carrying coil:
3
0
4 r
r
s
d
i
B
d
0 = permeability constant
exactly m/A
T
10
4 7
r
i
B
2
0
R
i
B
f
4
0
R
i
B
2
0
d
L
i
i
F b
a
ba
2
0
enc
i
s
d
B 0
r
R
i
B
2
0
2
in
B 0
r
iN
B
2
0
2
/
3
2
2
2
0
)
(
2
)
(
z
R
iR
z
B