Conductors, capacitors, dielectrics


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Conductors, capacitors, dielectrics

  1. 1. Jose & Brittany<br />Conductors, Capacitors, Dielectrics<br />
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  3. 3. Main Concepts of Electric Forces and Fields<br />Electric forces and electric fields are vectors, electric potentials are scalars<br />Electric fields point in the direction of the force on a positive test charge<br />Capacitance is the ratio of charge to the potential for a given conductor<br />The capacitance for a parallel-plate capacitor depends on the surface area of each plate, the plate seperation and the permittivity or dielectric constant<br />The capacitance of a system of parallel plates depends only on the physical characteristics of the capacitor (i.e. Surface area, plate seperation, dielectric material)<br />
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  5. 5. Important Vocabulary<br />Electrostatics – is the study of interaction between electric charges which are not moving <br />Conductors – are materials in which the electrons are free to move. Some examples such as silver, copper, gold, and mercury as metals<br />Electric Fields – exist in the space surrounding a charged particle or object<br />Capacitor- stores electric charge and consists of two conductors seperated by an insulator known as a dielectric<br />Dielectric – is an electrical insulator that can be polarized by an applied electrical field<br />Electric Current – is the rate of flow of electric charge. Used in Amperes (I) where 1 Ampere is 1 coulumb/second<br />Electrical Resistance refers to the opposition offered by a substance to the flow of electrical current. Unit of resistance is Ohm<br />
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  7. 7. Important Formulas<br />Electric Charge: q = n e ; where e = 1.6 X 10-19 C; (q) is the total charge on an object, (e) is the fundmental unit of charge, (n) is the number of total charges<br />Coulomb’s Law: F = k Q1 Q2/r2 ; where k = 9 X 109 N m2 /C2 ; (F) is the two charges exerted a force (Q) is the magnitude of the charge while (r) is the square of the distance between centers<br />
  8. 8. Important Formulas # 2<br />Electric Field: E = F/q or F = q E ; (E) is the magnitude of electric field, (F) force exerted om test charges, (q) is the magnittude of the charge of test particle<br />Electric Field to a Point Charge: E = k Q /r2 ; (E) is the magnitude of electric field, (F) force exerted om test charges, and (r) is the distance from the charge<br />
  9. 9. Important Formulas # 3<br />Electric Potential: V = PEa / q ; (PEa) is the potential energy, (q) per unit charge (V) is the electric potential at point<br />Capacitance: C = Q/V ; (C) is the ratio of the charge stored, (Q) is the potential difference, (V) is between the conducting surfaces <br />Electric Current: I = Q/t ; (I) is the electric current in Amperes<br />Electrical Resistance: R = p L/A ; (R) is the resistance of metal wire, (L) length, (A) cross-sectional area, (p) is the resistivity<br />Ohm’s Law: I = V/R or V = IR ; (I) stands for electric current and (V) stands for voltage of current and (R) stands for the resisitivity<br />
  10. 10. Main Concepts: Electric Circuits <br />An electrical network with a closed path<br />Measured in terms of the number of charge carriers, or<br />Particles containing a unit electric charge<br />The current flows through a resistance<br />
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  12. 12. Important Vocabulary<br />Electric circuit: a continuous closed path in with electric charges can flow<br />Electric current: flow of charged particles; conventionally, flow of positive charges<br />Electric power: the rate at which work is done or energy is dissipated through a resistor<br />Electrical resistance: the ratio of the voltage across a device to the current running through it<br />Capacitor: two oppositely charged conductors used to store charge and energy in an electric field between them<br />Resistor: device designed to have a specific resistance<br />Resistivity: the constant which relates the resistance of a resistor to its length and cross sectional area<br />
  13. 13. Vocabulary Continued<br />Ammeter: device used to measure electrical current<br />Ampere: unit of electrical current equal to one coulomb per second<br />Battery: device that converts chemical energy into electrical energy, creating a potential difference<br />Voltage: the potential difference between the positive and negative terminals of a battery<br />
  14. 14. Formulas<br />
  15. 15. Ohm’s Law<br />The ratio of voltage to current in a circuit is a constant called resistance<br />Measured in ohm: one volt per ampere<br />