Question

An e.m.f.$E = 4\cos(1000t)$ volt is applied to an LR-circuit of inductance 3 mH and resistance 4 ohms. The amplitude of current in the circuit is

• A. $\frac{4}{\sqrt{7}}A$
• B. 1.0 A
• C. $\frac{4}{7}A$
• D. 0.8 A

Answer 1

Answer: (D)

0.8 A

Answer 2

$i = \frac{V}{Z} = \frac{4}{\sqrt{4^{2} + (1000 \times 3 \times 10^{- 3})^{2}}} = 0.8A$