Question

An inductive coil connected to a 200 V, 50 Hz AC supply with 10 A current flowing through it dissipates 1000 W. Which of the following will have least value?

(a) Resistance R

(b) Reactance XL

(c) Impedance Z

(d) Reactance XC

I had been asked this question in an online quiz.

I want to ask this question from Problems Involving Standard Time Functions in section Application of the Laplace Transform in Circuit Analysis of Network Theory

Answer 1

The correct choice is (a) Resistance R

Easiest explanation: Power dissipated is given by,

I^2R = 1000 W

Hence, R = \(\frac{1000}{100}\)

Or, R = 10 Ω

Impedance Z = \(\frac{V}{I} = \frac{200}{10}\)

Or, Z = 20 Ω

Reactance XL = \(\sqrt{Z^2 – R^2}\)

= \(\sqrt{20^2 – 10^2}\)

∴ XL = 17.3 Ω.