Question

 What is the resistance of a lightbulb that uses an average power of 75.0 W when connected to a 60.0-Hz power source having a maximum voltage of 170 V?

 

Determine the rms voltage first since the given 60Hz power source suggest AC current. 

  

  

Then, compute for the arms current.

  

  

Since from Ohm's Law, V=IR

The resistance of the light bulb may be calculated using the formula