Electrical Resistance Exercise, Please Help.

claudia

12th May 2007 - 02:22 PM

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.

Darren

12th May 2007 - 03:13 PM

QUOTE (claudia+May 12 2007, 02:22 PM)

Hi there,

If 220V source is root mean square(r.m.s.) assuming it is sinsoidal or 220V d.c. and also we assume the light bulb impedance is pure resistance and non reactive then yes you are correct.

Keep well
Darren

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