Advance sunrise and delayed sunset
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The sunrise appears earlier and sunset appears later than the actual positions due to atmospheric refraction of sunlight. As sunlight enters the Earth's atmosphere, it follows a curved path through air of varying density, causing the observer to see the sun two minutes before it reaches the horizon at sunrise and two minutes after it dips below the horizon at sunset. This atmospheric refraction increases the overall duration of daylight by four minutes.
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formation of rainbow
A rainbow is formed when sunlight interacts with water droplets in the atmosphere through refraction, dispersion, and total internal reflection within the droplets. The sunlight separates into visible color spectrums as it enters and reflects within the droplets, with red light refracting less than blue light. A primary rainbow results from one internal reflection in a droplet and appears at an angle of 42 degrees, while a secondary rainbow comes from two internal reflections and is seen at an angle of 50 degrees.
atmospheric refraction
Atmospheric refraction is the bending of light as it passes through the atmosphere due to changes in air density with altitude. This causes distant objects to appear elevated, lowered, or shimmering. It also causes advanced sunrise and delayed sunset, the apparent elevation of stars, and the lack of twinkling in planets. Refraction makes the sun appear larger and flattened at sunrise/sunset but circular at noon. It can also create mirages by refracting light to appear as reflected sky.
Atmospheric refraction ppt
Atmospheric refraction causes several optical phenomena including advanced sunrise and delayed sunset, twinkling of stars, apparent flattening of the sun's disc at sunrise and sunset, and mirages. Refraction occurs when light travels from one medium to another of different densities, such as from air to air of different temperatures in the atmosphere. This causes the light's path to bend and results in the sun appearing above the horizon before actual sunrise or remaining visible after sunset. Stars twinkle due to the fluctuating refractive index of the lower atmosphere bending the starlight. Planets do not twinkle as their larger apparent size averages out the fluctuations. Mirages occur due to variations in the refractive index profile of the atmosphere distorting the appearance
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PPT on refraction and lenses by pg
This document discusses refraction and lenses. It begins by explaining that refraction occurs when light passes from one medium to another, causing its velocity and path to change. It then discusses how lenses work, noting that there are two basic types: convex and concave lenses. Convex lenses converge light rays to a focal point, while concave lenses diverge light rays. The document provides examples of how light rays behave when passing through lenses and the characteristics of images formed, such as location, size, and orientation. It concludes by introducing the lens formula, which relates the focal length, object distance, and image distance.
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atmospheric refraction
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Atmospheric refraction ppt
Atmospheric refraction causes several optical phenomena including advanced sunrise and delayed sunset, twinkling of stars, apparent flattening of the sun's disc at sunrise and sunset, and mirages. Refraction occurs when light travels from one medium to another of different densities, such as from air to air of different temperatures in the atmosphere. This causes the light's path to bend and results in the sun appearing above the horizon before actual sunrise or remaining visible after sunset. Stars twinkle due to the fluctuating refractive index of the lower atmosphere bending the starlight. Planets do not twinkle as their larger apparent size averages out the fluctuations. Mirages occur due to variations in the refractive index profile of the atmosphere distorting the appearance
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Ppt on atmospheric refraction
Atmospheric refraction is the deviation of light as it passes through the atmosphere due to changes in air density with altitude. This causes several optical phenomena including mirages and the apparent shimmering or rippling of distant objects. It also results in the sun appearing before actual sunrise and after actual sunset due to light bending as it passes through changing air densities in the atmosphere. Stars appear to twinkle due to their light continuously refracting as it passes through atmospheric layers of changing density, while planets do not twinkle as much due to their larger apparent size. The sun also appears larger during sunrise and sunset compared to noon due to greater refraction of light through more dense lower atmosphere.
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The document discusses several natural optical phenomena caused by the interaction of sunlight with Earth's atmosphere and surfaces. It describes how rainbows are formed by the dispersion, internal reflection, and refraction of sunlight within water droplets. It also explains how atmospheric refraction causes stars to appear higher and twinkle, while planets do not twinkle significantly due to their closer proximity. Finally, it discusses how atmospheric refraction makes the sun visible for a few minutes before sunrise and after sunset, even though the sun has physically dipped below the horizon.
Atmospheric refraction
Refraction is the change in direction of light when passing from one medium to another of different density. Snell's law states that the ratio of sines of the angle of incidence and refraction is equal to the ratio of refractive indices of the two media. Due to refraction, the sun appears above the horizon before actual sunrise and remains visible after sunset. Stars twinkle because their light refracts through Earth's fluctuating atmosphere, while planets do not twinkle as they appear as extended sources when viewed. Refraction also causes mirages and the apparent flattening of the sun near the horizon.
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This document describes Whetstone's bridge circuit used to measure an unknown resistance. It notes potential errors from non-uniform wire thickness or contact resistance, and how they can be minimized by taking multiple readings and calculating the average. It also provides the formula to calculate the resistance of a galvanometer used to read the null point in the circuit. Finally, it includes a multiple choice question testing understanding of the equivalent resistance in the Whetstone's bridge circuit.
Aldehydes Ketones and Carboxylic Acids - JEE Main 2015
This document contains 10 multiple choice questions about aldehydes, ketones, and carboxylic acids. The questions cover topics like ketone group placement, carbonyl carbon hybridization, definitions of aldehydes and acetone, IUPAC naming of compounds, and thermal decomposition reactions of calcium salts producing aldehydes. An answer key is provided at the end.
Physics - Current Electricity Notes for JEE Main 2015
Kirchhoff's laws are used to calculate currents and voltages in circuits with multiple branches or energy sources. Kirchhoff's Current Law (KCL) states that the algebraic sum of currents at any node is zero. Kirchhoff's Voltage Law (KVL) states that the algebraic sum of voltages around any closed loop is equal to the sum of the voltage drops and rises along that loop. Both laws are based on the principle of conservation of charge and energy in electric circuits.
Enhancement in Food Production Exercises - MH-CET 2015
The document contains 10 multiple choice questions about plant breeding and the green revolution. It tests knowledge about the objectives of plant breeding including developing varieties that are suitable for cultivation, have better yield, and disease resistance. It also contains questions about improving tolerance for environmental stress factors like drought through breeding. Additional questions cover topics like germplasm collection, increased wheat and rice yields during the green revolution due to semi-dwarf varieties, specific high yielding varieties of wheat and rice developed in India. An answer key is provided at the end.
Properties of Solids and Liquids Notes - JEE Main 2015
1. Interatomic forces are electrical forces between atoms due to electrostatic interactions between their charges. These forces are strongest when atoms are about 10-10 meters apart.
2. Intermolecular forces, also called Van der Waals forces, are weaker electrical forces between molecules due to electrostatic interactions between their charges. These forces are strongest when molecules are about 10-9 meters apart.
3. Both interatomic and intermolecular forces are attractive at normal distances but become repulsive if distances decrease further. The potential energy is lowest at normal distances.
12th Chemistry P-block elements Notes for JEE Main 2015
This document provides information about oxygen and the group 16 elements. It discusses the properties of oxygen and how it differs from other group 16 elements. Some key points include:
- Oxygen exists as a diatomic gas while other group 16 elements form polyatomic solids and liquids.
- Oxygen exhibits different oxidation states and bonding abilities compared to other group 16 elements due to its small size and high electronegativity.
- Common preparation methods for oxygen include thermal decomposition of oxygen-rich salts, metallic oxides, and the reaction of sodium peroxide or potassium permanganate with water.
Organisms and Environment Exercise - MH-CET 2015
i. Carbon dioxide plays a crucial role in global warming by trapping infrared radiation in the atmosphere and increasing temperatures. CO2 levels have increased 50% over the last 50 years due to human activities like burning fossil fuels.
ii. Agrochemicals kill beneficial soil microbes and cause pest resistance, pollution, bioaccumulation of toxic chemicals, and health issues for farmers. Only 15% of chemicals hit targets, while the rest pollutes nearby areas.
iii. The carbon cycle involves the exchange of carbon between the atmosphere, oceans, plants, animals and fossil fuels through photosynthesis, respiration, and the weathering of carbonate rocks. Human activity like burning fossil fuels is greatly interfering with the natural carbon cycle
Communication System Theory for JEE Main 2015
There are three main types of space communication: ground wave propagation, sky wave propagation, and space wave propagation. Ground wave propagation uses low frequencies between 500kHz to 1500kHz for medium wave radio transmission over short distances. Sky wave propagation uses very low and high frequency waves that can reflect off the ionosphere to allow long distance communication. Space wave propagation uses electromagnetic waves between 30MHz to 300MHz that travel directly between transmitting and receiving antennas within line of sight of each other over distances up to 35km. Satellite communication is used to transmit waves beyond 30MHz that cannot be transmitted through other methods. Satellites receive, amplify, and retransmit signals to allow global communication with advantages like long distance coverage and ability to transmit large
Genetic Engineering and Genomics Notes - MH-CET 2015
This document discusses genetic engineering and DNA fingerprinting. It introduces genetic engineering as a technique where desired genes can be cut from one organism and joined to other genes to introduce into other cells. This allows for novel products to be produced. It then discusses DNA fingerprinting, a technique used to identify individuals based on their unique DNA profiles. DNA fingerprinting analyzes variable number tandem repeats, non-coding regions of DNA that differ between individuals and can be used as genetic markers for personal identification. The document outlines the process of DNA fingerprinting, which involves isolating and replicating DNA from a sample, cutting it with restriction enzymes, separating fragments via electrophoresis, transferring to membranes, and using probes to identify location of repeats to create unique
Notes and Important Points on Circular Motion for JEE Main 2015
Motion can be linear, circular, or oscillatory. Circular motion involves a particle moving along the circumference of a circle. The position vector is drawn from the center of the circle to the particle and the angular displacement is the angle traced by the position vector. Angular velocity is the rate of change of the angular displacement with respect to time, while angular acceleration is the rate of change of the angular velocity. Uniform circular motion describes a body moving at a constant linear speed or angular velocity along a circular path.
Notes and Important Points on Electrochemistry - JEE Main 2015
This document provides an introduction to electrochemistry and discusses key concepts such as electrolytes, electrolytic cells, and the preferential discharge theory of electrolysis. Some main points:
1) Electrolytes are substances that undergo decomposition into ions when an electric current is passed through them in solution. Electrolytic cells, also called voltameters, are devices used to carry out electrolysis where electrical energy is converted to chemical energy.
2) During electrolysis, oxidation occurs at the anode where anions are released and reduction occurs at the cathode where cations gain electrons. The preferential discharge theory states that ions with lower discharge potentials will be discharged first at the appropriate electrode.
3) Examples of products formed
Physics Sound and Waves for JEE Main 2015 - Part I
The document discusses different types of motions including translational, rotational, oscillatory, and vibrational motion. It also defines key terms related to oscillations such as period, frequency, amplitude, damped oscillations, and sustained oscillations. Regarding waves, it describes longitudinal and transverse waves, and defines properties such as wavelength, velocity, and how velocity is related to frequency and wavelength. It also provides formulas for calculating the velocity of longitudinal and transverse waves in different media.
Notes and Important Points on Solid State - JEE Main 2015
(1) Graphite is used as a lubricant because its layers can slide over one another when a shearing force is applied. This is due to the weak van der Waals forces between layers consisting of hexagonal carbon networks.
(2) Iron is strongly ferromagnetic because it has four unpaired electrons in its electronic configuration.
(3) Ice is lighter than water because ice has a hexagonal crystal structure with hydrogen bonding that leaves almost half the space vacant, whereas water occupies spaces more closely when ice melts.
Study material 12th Physics - Wave Theory of Light Part II
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- Examples of how polaroid materials are used to absorb one polarized ray and transmit the other ray are provided. Common uses of polaroid materials include reducing glare in car headlights, 3D movie cameras, analyzing polarized light, and LCD screens.
Physics in day to day life Notes for JEE Main 2015
Physics principles are present in many everyday activities and technologies. Motion follows Newton's laws of motion. Sound is produced by vocal cord vibrations. Food digestion converts chemical to mechanical energy for work. Electricity in homes comes from hydroelectric projects that convert water's mechanical energy to electrical energy using dynamos. Refrigerators use thermodynamics principles. Pressure cookers, washing machines, music systems, and computers all apply physics concepts. Automobiles, trains, and aircraft rely on physics concepts. Vision works similarly to cameras through physics principles. Writing involves physics properties.
Summarized notes on Interference and Diffraction for JEE Main
The document discusses the principles of interference and diffraction of light waves. It explains the superposition principle, and conditions for constructive and destructive interference. Constructive interference occurs when the path difference between waves is equal to integer multiples of the wavelength, resulting in brighter spots. Destructive interference occurs when the path difference is equal to odd integer multiples of half the wavelength, producing darker bands. Young's experiment is described as demonstrating the interference of light. Methods for measuring the wavelength of light using a biprism and the interference pattern it produces are also outlined.
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