Calculating Electric and Magnetic Fields from Radiation Emitted by a 100 W Bulb

[erisedk]

Homework Statement

Calculate electric field and magnetic field produced by radiation emitted by a 100 W bulb at a distance of 1 m if radiation efficiency is only 5%.

Homework Equations

The Attempt at a Solution

I only know how to find intensity due to the bulb:
I = P/4πr² = 5/4π W/m²
I have absolutely no idea how to find the electric and magnetic field from that information.
I do know that B = E/c, so I just need to find one of those.

 

[jtbell]

I have absolutely no idea how to find the electric and magnetic field from that information.

Look in your textbook (or Google) for an equation for the power (density) carried by an electromagnetic wave. It can be expressed in terms of either the electric or magnetic field. It's a standard equation so it should be in your book if it has that exercise.

 

[erisedk]

Got it, I = (εE^2)(c).
No, it's not a textbook problem. And my book doesn't have much on this.
Thanks!

 

[jtbell]

Well, it sure looks like a textbook or exam problem. I've given similar problems to students many times.