Question

In series 'LR' circuit and in series 'RC' circuit, same current is flowing. If the frequency of e.m.f. of a.c. is increased for both the circuits, the impedance will ____________.

Options

• increase in 'LR' circuit and decrease in 'RC' circuit

• decrease in both the circuits

• increase in both the circuits

• decrease in 'LR' circuit and increase in 'RC' circuit

Answer 1

In series 'LR' circuit and in series 'RC' circuit, same current is flowing. If the frequency of e.m.f. of a.c. is increased for both the circuits, the impedance will increase in 'LR' circuit and decrease in 'RC' circuit.

Explanation:

The inductive reactance is given by `"X"_"L" = 2pi"fL"` and the capacitive reactance is given by `"X"_"C" = 1/(2pi"fc").` When frequency f increases X_L increases while X_C decreases.