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Current Electricity

Question
CBSEENPH12038142

Electromagnetic waves travel in a medium at a speed of 2 × 108 ms-1. The relative permeability of the medium is 1.0. Calculate the relative permittivity.

Solution

Given,
Speed of electromagnetic waves, v = 2 × 108 m/s
Relative permeability of the medium = 1
Speed of light, C = 3 × 108 m/s 

Using the formula of speed of electromagnetic wave in a medium,
                        v = 1με
                        v = 1μ0μr(ε0εr)
                        v = 1μ0 ε0 × 1μr εr

Therefore,
Relative permittivity,
                         εr = c2v2 μr   = 3 × 10822 × 1082 ×1    = 2.25

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