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  • The electric and magnetic fields of an electromagnetic wave are given by: <img alt="E(x, t)=50 \cos (\omega t-k x) \mathrm{V} / \mathrm{m} B(x, t)=4 \cos (\omega t-k x) \mathrm{T}

The electric and magnetic fields of an electromagnetic wave are given by:


E(x, t)=50 \cos (\omega t-k x) \mathrm{V} / \mathrm{m} B(x, t)=4 \cos (\omega t-k x) \mathrm{T}

where x is the position, t is the time,  \omega = 3 \times 10^8 rad/s and k = 5 \times 10^5 m^{-1}. What is the speed of the electromagnetic wave in a vacuum?

Option: 1

1.5 \times 10^8 m/s


Option: 2

2.0 \times 10^8 m/s


Option: 3

2.5 \times 10^8 m/s


Option: 4

3.0 \times 10^8 m/s


Answers (1)

best_answer

Correct option 4)  3.0 \times 10^8 m/s

The speed of electromagnetic waves in vacuum is given by c = \frac{1}{\sqrt{\epsilon_0 \mu_0}}, where \epsilon_0 is the permittivity of free space and \mu_0is the permeability of free space. The electric field and magnetic field amplitudes are given as E_0 = 50 V/m and B_0 = 4 Trespectively. Therefore, we can use the relation E_0/B_0 = c to find the speed of the wave, which is 3.0 \times 10^8 m/s.

 

Posted by

Devendra Khairwa

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