Question

RL Circuits:

A) As the frequency in an RL circuit increases, XL increases or decreases? If the

frequency is very, very high, the impedance Z is approximately XL or R?

B) .A series RL circuit of 100W and 0.1H is connected to a 12V, 200Hz voltage. Calculate the current in the circuit.

** Please draw visual diagrams for both problems please

Answer 1

Xl = (2 *pi * f * L)

As frequency increases Xl increases

For very large frequency Xl>> R, so the circuit is indcutive.

Z is approximately equal to Xl.

R = 100 Ohm

L = 0.1 H

f = 200 Hz

impedance is

Z = 100 + j(2 *pi * f * L)

Z = 100 + j * (2 * pi * 200 * 0.1)

Z = 100 + j * 125.64

Z = sqrt(100^2 + 125.64^2)

Z = 160.6 Ohm

current in the circuit = V/Z

current in the circuit = 12/160.6

current in the circuit = 0.075 A = 75 mA

the current in the circuit is 75 mA