Electrical Resistance Exercise, .

[claudiadeluca]

Please help with the following exercise:

How much should the electrical resistance of a light bulb be in order to consume a power of 60W if a voltage of 220V is applied?

This is how I solved it:

Power= Voltage^2 / Resistance

60W = 220V^2 / R

R = 807 ohms

Is it correct? Thank you.

 

[Astronuc]

Yes - the answer is correct.

for DC, Power = Voltage * Current, or P = V*I, but I = V/R, so

P = V²/R.

In this application, V is the potential difference driving the current I through resistance R.

When solving problems, it is best to write out the applicable equations so as to check one's understanding of the physics.