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Current Electricity

Question
CBSEENPH12038079

Suppose that the electric field part of an electromagnetic wave in vacuum is E = {(3.1 N/C) cos [(1.8 rad/m) y + (5.4 × 106 rad/s)t]}i^.  What is the wavelength λ?

Solution

Given,
Electric field, E = {(3.1 N/C) cos [(1.8 rad/m) y + (5.4 × 106 rad/s)t]}i^. 

Comparing the given equation with the equation
 E = E0 cos (ky + ωt) i a

Therefore, we get 

Amplitude of electric field, E0 = 3.1 NC-1Wave vector, k = 1.8 rad m-1Angular frequency, ω = 5.4 × 106 rad s-1 .

We know that,
                              ω = 2π v
               5.4 × 106 = 2π v = 2π × cλ
                 λ = 2πc5.4 × 108  = 2π × 3 × 1085.4 × 108

                      = 3.5 m 
which is the required value of wavelength.