The power, in watts, dissipated as heat in a resistor varies jointly with the resistance, in ohms, and the square of the current, in amperes.A 15-ohm resistor carrying a current of 1 ampere dissipates 15 watts.
How much power is dissipated in a 80-ohm resistor carrying a current of 3 amperes?
A) $ P = 80 \mathrm { Watts }$
B) $P = 8$ Watts
C) $P = 3$ Watts
D) $P = 720 \mathrm { Watts }$
E) $P = 24 \mathrm { Watts }$

Question

The power, in watts, dissipated as heat in a resistor varies jointly with the resistance, in ohms, and the square of the current, in amperes.A 15-ohm resistor carrying a current of 1 ampere dissipates 15 watts.
How much power is dissipated in a 80-ohm resistor carrying a current of 3 amperes? 
A) $ P = 80 \mathrm { Watts }$
B) $P = 8$ Watts
C) $P = 3$ Watts
D) $P = 720 \mathrm { Watts }$
E) $P = 24 \mathrm { Watts }$

Quizplus · Accepted Answer

The power dissipated in a resistor is given by $P = I^2R$, where $I$ is the current in amperes and $R$ is the resistance in ohms. For a 80-ohm resistor carrying a current of 3 amperes, $P = 3^2 \times 80 = 9 \times 80 = 720$ Watts.

The Power, in Watts, Dissipated as Heat in a Resistor P=80Watts P = 80 \mathrm { Watts }P=80Watts

The Power, in Watts, Dissipated as Heat in a Resistor $P = 80 \mathrm { Watts }$