If the rms value of the electric field in an electromagnetic...

Name: Problem 43, Chapter 25: Physics
Uploaded: 2021-03-26T07:22:19-08:00
Duration: 55 s
Channel: Khoobchandra Agrawal
Description: If the rms value of the electric field in an electromagnetic wave is doubled, (a) by what factor does the rms value of the magnetic field change? (b) By what factor does the average intensity of the wave change?

If the rms value of the electric field in an electromagnetic wave is doubled, (a) by what factor does the rms value of the magnetic field change? (b) By what factor does the average intensity of the wave change?

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Key Concepts

Intensity of Electromagnetic Waves

The intensity of an electromagnetic wave is a measure of the energy transmitted per unit area per unit time, and it is proportional to the square of the amplitude of the electric field (or equivalently the magnetic field). Consequently, if the electric field amplitude is doubled, the square law dictates that the intensity increases by a factor of four.

Root Mean Square (RMS) Values

The root mean square (rms) value provides a measure of the effective or average magnitude of a time-varying field such as an electromagnetic wave. This measure is particularly useful when dealing with quantities like power and intensity because it reflects the equivalent steady-state value that would produce the same energy effect as the actual time-varying wave.

Electromagnetic Wave Field Relationship

In electromagnetic waves, the electric and magnetic fields are intrinsically linked by a fixed ratio defined by the speed of light (c in vacuum), typically expressed as E = cB. This relationship ensures that any change in the electric field is accompanied by a proportional change in the magnetic field, preserving the overall dynamics of wave propagation.

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