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

In summary, the task is to calculate the electric field and magnetic field produced by radiation emitted by a 100 W bulb at a distance of 1 m, with a radiation efficiency of 5%. The intensity can be found using the equation I = P/4πr^2 = 5/4π W/m^2. The power carried by an electromagnetic wave can be expressed in terms of either the electric or magnetic field, and can be found using the equation I = (εE^2)(c). This is a common problem found in textbooks and exams.
  • #1
erisedk
374
7

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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  • #2
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.
 
  • #3
Got it, I = (εE^2)(c).
No, it's not a textbook problem. And my book doesn't have much on this.
Thanks!
 
  • #4
Well, it sure looks like a textbook or exam problem. I've given similar problems to students many times. :oldwink:
 

1. What are electromagnetic waves?

Electromagnetic waves are a type of energy that is produced by the movement of electrically charged particles. They are characterized by their oscillating electric and magnetic fields, and they can travel through a vacuum at the speed of light.

2. What are the properties of electromagnetic waves?

Electromagnetic waves have several properties, including wavelength, frequency, amplitude, and velocity. The wavelength is the distance between two consecutive wave peaks, while the frequency is the number of waves that pass by a given point in one second. The amplitude is the maximum displacement of the wave from its resting position, and the velocity is the speed at which the wave travels.

3. How are electromagnetic waves produced?

Electromagnetic waves are produced when an electrically charged particle accelerates. This acceleration creates a change in the electric and magnetic fields, which then propagate through space as an electromagnetic wave.

4. What is the electromagnetic spectrum?

The electromagnetic spectrum refers to the entire range of electromagnetic waves, from the longest radio waves to the shortest gamma rays. It includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

5. How are electromagnetic waves used in everyday life?

Electromagnetic waves have many practical applications in everyday life, including communication through radio waves, microwave ovens, infrared sensors for remote controls and heat detection, visible light for vision, and X-rays for medical imaging. They are also used in technologies such as radar, GPS, and satellite communication.

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