Question

A 200 V lamp takes a current of 0.5 amp and produces a total flux of 3000 lumens. Calculate the efficiency of the lamp.

• A. 15%
• B. 60%
• C. 30%
• D. 75%

Hint:

Efficiency of lamps is a measure of how much electrical power is converted into useful light output.

Answer 1

The Correct Option is C

The efficiency \( \eta \) of the lamp is given by the formula: \[ \eta = \frac{\text{useful flux output}}{\text{electrical power input}} \times 100 \] The electrical power input is: \[ P = V \times I = 200 \, \text{V} \times 0.5 \, \text{A} = 100 \, \text{W} \] The useful flux output is 3000 lumens. Assuming the conversion factor from lumens to watts is \(1 \, \text{watt} = 683 \, \text{lumens}\) for 100% efficiency: \[ \text{Efficiency} = \frac{3000}{683 \times 100} \times 100 \approx 30% \]