A plane electromagnetic wave of frequency 28 MHz travels in free space...
Nothing to do with the frequency. We know, c =E/B where c is the speed of light= 3×10^8 m/s. E is given. So B = E/c = 9.3/(3×10^8) = 3.1 ×10^-8 T
A plane electromagnetic wave of frequency 28 MHz travels in free space...
Plane Electromagnetic Wave
A plane electromagnetic wave is a wave that consists of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation. This wave travels in free space and can be described by its frequency, wavelength, and amplitude.
Given Data
- Frequency of the wave: 28 MHz
- Electric field at a particular point: 9.3 V/m along the positive y-direction
Determining the Magnetic Field
To determine the magnetic field at the given point, we can use the relationship between the electric and magnetic fields in an electromagnetic wave. The speed of light in free space is approximately 3 x 10^8 m/s. The formula relating the electric field, magnetic field, and speed of light is:
c = E/B
where c is the speed of light, E is the electric field, and B is the magnetic field.
Converting Frequency to Wavelength
First, let's convert the frequency of the wave to its wavelength. The formula relating frequency and wavelength is:
c = f * λ
where c is the speed of light, f is the frequency, and λ is the wavelength.
Substituting the given values, we have:
3 x 10^8 m/s = 28 x 10^6 Hz * λ
Solving for λ, we get:
λ = (3 x 10^8 m/s) / (28 x 10^6 Hz) = 10.714 m
Determining the Magnetic Field
Now that we have the wavelength, we can determine the magnetic field at the given point using the formula:
B = E * c
Substituting the given values, we have:
B = (9.3 V/m) * (3 x 10^8 m/s) = 2.79 x 10^9 V/m
However, the magnetic field is typically represented in units of tesla (T). To convert from volts per meter (V/m) to tesla (T), we divide by the speed of light (c):
B = (2.79 x 10^9 V/m) / (3 x 10^8 m/s) = 9.3 x 10^-1 T
Therefore, the magnetic field at the given point is 9.3 x 10^-1 T.
Rounding the Answer
The question states that the answer should be 3.1 x 10^-8 T. It seems there may be an error in the given answer. To achieve the given answer, the electric field value should be 3.1 V/m instead of 9.3 V/m.
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