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Key Terms

instrument that measures current
electromotive force (emf)
energy produced per unit charge, drawn from a source that produces an electrical current
equivalent resistance
resistance of a combination of resistors; it can be thought of as the resistance of a single resistor that can replace a combination of resistors in a series and/or parallel circuit
internal resistance
amount of resistance to the flow of current within the voltage source
junction rule
sum of all currents entering a junction must equal the sum of all currents leaving the junction
Kirchhoff’s rules
set of two rules governing current and changes in potential in an electric circuit
loop rule
algebraic sum of changes in potential around any closed circuit path (loop) must be zero
potential difference
difference in electric potential between two points in an electric circuit, measured in volts
potential drop
loss of electric potential energy as a current travels across a resistor, wire, or other component
RC circuit
circuit that contains both a resistor and a capacitor
shock hazard
hazard in which an electric current passes through a person
terminal voltage
potential difference measured across the terminals of a source when there is no load attached
thermal hazard
hazard in which an excessive electric current causes undesired thermal effects
three-wire system
wiring system used at present for safety reasons, with live, neutral, and ground wires
instrument that measures voltage
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