Question

A current of 0.5 A flows in a 60 W light bulb when the voltage differences between the ends of the filament is 120 V. What is the resistance of the filament ?

Answer 1

Resistance = (voltage) / (current)

Resistance = (120 V) / (0.5 A)

Resistance = 240 ohms

Know what ?  There might be too much information given in this question.  I want to check, because it's possible that it might not even all fit together.

To calculate my answer, I only used the voltage and the current.  I didn't use the "60 watts", and I'm curious to know whether it even fits with the given voltage and current.

Power = (voltage) times (current).

Power = (120 V) times (0.5 A)

Power = 60 watts  

Well gadzooks and sure enough !  The three numbers given in the question all go together nicely.  

And not only THAT !

The answer could have been calculated by using ANY TWO of them.