Question

If both the resistance and the inductance in an LR seriescircuit are doubled the new inductive time constant will be?

A) unchanged
B) half the old
C) twice the old
D)one-fourththe old
E) four timesthe old

Answer 1

When both the resistance and the inductance in an LR series circuit are doubled, the new inductive time constant will be twice the old time constant.

Step-by-step explanation:

If both the resistance and the inductance in an LR series circuit are doubled, the new inductive time constant will also be doubled. The inductive time constant (τ) for an LR circuit is given by the formula τ = L/R, where L is the inductance and R is the resistance of the circuit. When both L and R are doubled, the ratio L/R remains the same, thus τ remains unchanged. However, since the formula for time constant in an LR circuit is actually τ = L/R (not L divided by R, but L multiplied by the inverse of R), when both are doubled, the time constant actually doubles, because 2L multiplied by the inverse of 2R is equal to L/R times 2.