Electricity

19A Static Electricity

• Electric Force: the field force between two charged objects

• Electric Fields

  • Electric Field: a three-dimensional region around a charged object that will apply a force on other charged objects within that region

  • Electric Potential Energy: energy that is stored by a charged object in an electric field. the quantity depends on the magnitude of the charges and the object’s position in the field

• Methods of Charging

  • Charging by Friction: the process by which an object can gain excess charge while being rubbed by another object

  • Charging by Conduction: the process by which one charged object can produce a second charged object by the two objects being placed in contact with each other and the excess charge being shared

  • Charging by Induction: the process by which one charged object can produce a second charged object by allowing the electric force to move excess charge onto the second object while the two objects are not in contact with each other

19B Current Electricity

• Electric Current

  • Current Electricity: electricity involving moving electric charges

  • Electric Current: the movement of electric charge through a complete loop

  • Electric Circuit: the loop through which current electricity can flow

  • Open Circuit: an incomplete electric circuit that prevents the movement of charge

  • Closed Circuit: a complete electric circuit that allows charge to flow

  • Direct Current: electric current in which electric charges move in only one direction

  • Conventional Current: the direction in a DC circuit that positive charges would flow; decided by agreement as the standard current direction

• Understanding Direct Current

1. The pump does work as it lifts the water to the storage tank, storing gravitational potential energy

2. The valve controls the flow of water

3. The water does work through the turbine to convert the energy into other forms

4. The water continues to flow until it returns to the pump

1. The battery stores energy. When needed, the battery transforms energy from chemical potential energy to electrical energy

2. The switch controls the flow of electricity

3. The charge carriers do work through the lamp as the electrical energy is converted to light and thermal energy

4. The change carriers continue moving through the circuit back to the battery

• alternating current: electric current in which the charge carriers change direction periodically

• Conductors and Insulators

  • electrical conductors: a material through which electric charge moves easily

  • electrical insulator: a material through which electric charge does not move easily

• Current, Voltage, and Resistance

  • ampere: the fundamental SI unit of electric current

  • ammeter: a meter used to measure electric current through a circuit

  • voltage: The “force” that moves electric charge carriers through an electric current; also called electric potential difference

  • voltmeter: a meter used to measure voltage

  • battery: a power source for DC electrical systems consisting of two or more electrochemical cells

  • ohm: the derived SI unit for electrical resistance

  • superconductor: a material with zero resistance

• ohm’s law: the law that states that the current in a circuit is directly related to the voltage and inversely related to the resistance

19C Circuits

• electrical load: an electrical device in a circuit that consumes electrical energy

• short circuit: an unintended path for an electric current

• Series and Parallel Circuits

  • series circuit: a circuit with only one path that electric current can take

  • parallel circuit: a circuit with multiple paths that electric current can take

• electrical power: the work per second done or produced by an electrical system

• Electrical Safety

  • fuse: an electrical safety device that opens the circuit by melting when an overheated condition occurs due to excessive current

  • circuit breaker: an electrical safety device consisting of an automatic switch that opens when there is too much current in a circuit

  • grounding: the act of providing a path for electrical charge to move into the earth

  • ground-fault interrupter: a safety device consisting of an outlet with a built-in circuit breaker