How to find the amplitudes and polarisation of travelling waves

In summary, the problem involves plane monochromatic waves propagating in free space parallel to the x-axis. The field strengths at the origin are given by Ez = E0 cos wt, Ey = 3E0 cos wt, cBz = E0 cos wt, and cBy = E0 cos wt. The task is to find the amplitudes and polarisations of the forward and backward travelling waves, as well as the net energy flux. The backward amplitude is determined to be 2E0 parallel to the y-axis, and the net flux is calculated to be E0^2/Z0. The forward amplitude can be easily derived from the given equation y = A cos(ωt + φ).
  • #1
faraaa
2
0

Homework Statement



Plane monochromatic waves are propagating in free space parallel to the x-axis
in both positive and negative directions. At the origin the fi eld strengths are
given by:
Ez = E0 cos wt Ey = 3E0 cos wt
cBz = E0 cos wt cBy = E0 cos wt
Find the amplitudes and polarisations of the forward and backward travelling
waves, and the net energy flux


The Attempt at a Solution



I only get the backward amplitude which is 2E0 parallel to y-axis and the net flux which is E0^2/Z0

Can anyone help to find the forward amplitude?
 
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  • #2
faraaa said:

Homework Statement



Plane monochromatic waves are propagating in free space parallel to the x-axis
in both positive and negative directions. At the origin the fi eld strengths are
given by:
Ez = E0 cos wt Ey = 3E0 cos wt
cBz = E0 cos wt cBy = E0 cos wt
Find the amplitudes and polarisations of the forward and backward travelling
waves, and the net energy flux


The Attempt at a Solution



I only get the backward amplitude which is 2E0 parallel to y-axis and the net flux which is E0^2/Z0

Can anyone help to find the forward amplitude?

$$ y=A\cos\left(\omega t+\phi\right) $$

Isn't the answer quite easy to derive now?:biggrin:
 

1. How do I calculate the amplitude of a travelling wave?

The amplitude of a travelling wave is the maximum displacement of a point on the wave from its equilibrium position. To calculate the amplitude, you can measure the distance from the peak of the wave to its equilibrium position or use the equation A = (1/2) (ymax - ymin) where ymax and ymin are the maximum and minimum values of the wave's displacement.

2. What is the relationship between wavelength and amplitude in a travelling wave?

There is no direct relationship between wavelength and amplitude in a travelling wave. Wavelength is the distance between two consecutive peaks or troughs of a wave, while amplitude is the maximum displacement of a point on the wave. However, in some cases, a shorter wavelength may result in a larger amplitude, but this depends on the properties of the medium through which the wave is travelling.

3. How can I determine the polarisation of a travelling wave?

The polarisation of a travelling wave refers to the direction in which the wave oscillates. To determine the polarisation, you can observe the motion of particles along the direction of the wave's propagation. If the particles move in a single direction, the wave is said to be polarised. If the particles move in multiple directions, the wave is unpolarised.

4. Can the amplitude of a travelling wave change over time?

Yes, the amplitude of a travelling wave can change over time. This is known as amplitude modulation and occurs when the amplitude of the wave varies periodically. Amplitude modulation is commonly used in communication systems to transmit information through changes in amplitude.

5. How does the amplitude of a travelling wave affect its energy?

The amplitude of a travelling wave is directly proportional to its energy. This means that a higher amplitude wave carries more energy than a lower amplitude wave. In terms of energy transfer, a larger amplitude wave is capable of transferring more energy to the medium it is propagating through.

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