Question

In a series RLC circuit having resistance R = 2 Ω, and excited by voltage V = 1 V, the average power is 250 mW. The phase angle between voltage and current is ___________

(a) 75°

(b) 60°

(c) 15°

(d) 45°

Answer 1

The correct choice is (d) 45°

The best explanation: VI cos θ = 0.25 or I cos θ = 0.25

Or, Z cosθ = 2

Or, \(\frac{V}{I}\) cos⁡θ = 2

Or, cos θ = \(\frac{1}{\sqrt{2}}\)

So, from the above equations, cos θ = 0.707 and θ = 45°.