A heater is plugged into the same 120-V AC outlet as an 800-W hair dryer.If the total rms current drawn is 16.7 A,then calculate the power rating of the heater.
A)2000 W
B)800 W
C)3200 W
D)1200 W
E)2800 W

Question

Quizplus · Accepted Answer

We can use the formula P = VI, where P is power, V is voltage, and I is current. 
For the hair dryer, P = 800 W and V = 120 V. We can rearrange the formula to solve for the current: 
I = P/V = 800/120 = 6.67 A 
So the current drawn by the hair dryer is 6.67 A. 
The total current drawn is 16.7 A, so the current drawn by the heater is: 
I_heater = 16.7 A - 6.67 A = 10.03 A 
Finally, we can use the formula again to solve for the power of the heater: 
P_heater = V * I_heater = 120 V * 10.03 A = 1203.6 W ≈ 1200 W. 
Therefore, the power rating of the heater is 1200 W, option D.

A Heater Is Plugged into the Same 120-V AC Outlet