Question

The power consumption of an electrical device varies directly with the square of the voltage applied. If a device consumes 150 watts when the voltage is 120 volts, how much power (in watts) will it consume at 240 volts?

• A. 550
• B. 650
• C. 500
• D. 600

Answer 1

Answer:

D. 600

Since power varies directly with the square of voltage:

$P \propto V^2$

So,
$\frac{P_1}{P_2} = \frac{V_1^2}{V_2^2}$

Given:
$(P_1 = 150) W, (V_1 = 120) V, (V_2 = 240) V$

$P_2 = 150 \times \left(\frac{240}{120}\right)^2$
$= 150 \times (2)^2$
$= 150 \times 4$
$= 600$

Final Answer:

600 watts