Question

A toaster filament dissipates 100W when plugged into a 130V outlet; assuming a constant filament resistance, identify the power dissipated by the filament when the toaster is when plugged into a 120V outlet. A. 85W OB.92W C. 100W OD. 108W E. 120W

Answer 1

Answer:

A. 85 W

Explanation:

case 1: toaster is connected to 130 V outlet

P = Power rating of toaster = 100 W

R = Resistance of the filament

V = Voltage of the source = 130 Volts

Power is given as

$P = \frac{V^{2}}{R}$

$100 = \frac{130^{2}}{R}$

R = 169 ohm

case 2: toaster is connected to 120 V outlet

P = Power dissipated

R = Resistance of the filament = 169 ohm

V = Voltage of the source = 120 Volts

Power dissipated  is given as

$P = \frac{V^{2}}{R}$

$P = \frac{120^{2}}{169}$

P = 85 W