30.
Because of the property of inductance to oppose a change in current, a certain amount of time is required
for current change. The time it takes the current in a circuit containing only resistance, inductance, and a d-
c voltage source to change 63.2 percent of its value, is known as the L/R TIME CONSTANT. The time
constant is determined by the ratio of circuit inductance to circuit resistance. The mathematical equation is:
where TC = time constant in seconds
L = circuit inductance in henrys
R = circuit resistance in ohms
Calculate the L/R time constant of a circuit with 2h of inductance and 10 of resistance.
31.
On the inductive waveforms shown below, label the current and voltage waveform.
1-19
IT0353
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