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

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Homework Help Overview

The discussion revolves around calculating the electric and magnetic fields generated by the radiation emitted from a 100 W bulb, considering a radiation efficiency of 5% at a distance of 1 meter. The subject area includes concepts from electromagnetism and wave propagation.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the intensity of radiation and its relation to electric and magnetic fields. One participant attempts to calculate intensity but expresses uncertainty about deriving the electric and magnetic fields from that information. Others suggest looking for standard equations related to electromagnetic waves.

Discussion Status

The discussion is ongoing, with participants exploring different approaches to relate intensity to electric and magnetic fields. Some guidance has been offered regarding standard equations, but there is no explicit consensus on the method to proceed.

Contextual Notes

One participant notes that the problem does not appear to be from a textbook, indicating potential challenges in finding relevant equations or examples. There is also a suggestion that the problem resembles typical textbook or exam questions.

erisedk
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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.
 
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erisedk said:
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.
 
Got it, I = (εE^2)(c).
No, it's not a textbook problem. And my book doesn't have much on this.
Thanks!
 
Well, it sure looks like a textbook or exam problem. I've given similar problems to students many times. :oldwink:
 

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