Question

An incandescent lightbulb is rated at 120 Watts when plugged into a 200 V-rms household outlet. Calculate the resistance of the filament and the rms current. g

Answer 1

• The resistance of the filament is 333.33 ohms

• The rms current is 0.6 A

Step-by-step explanation:

Given;

output power of the incandescent lightbulb , P = 120 W

input voltage, V = 200 V

The resistance of the filament is calculated as;

`P = (V^2)/(R)`

Where;

R is the resistance of the filament

`R = (V^2)/(P) \\\\R = (200^2)/(120) \\\\R = 333.33 \ ohms`

The rms current is given as;

`P = I_(rms) V_(rms)\\\\I_(rms) = (P)/(V_(rms)) \\\\I_(rms) =(120)/(200)\\\\ I_(rms) = 0.6 \ A`