InterviewSolution
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InterviewSolution
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Suppose that the electric field of an electromagnetic wave in vacuum is `E={(3.0 N //C) cos [1.8 rad//m) y +(5.4 xx 10^6 rad // s)t]}hat i` (a) What is the direction of propagation of wave? (b) What is the wavelength lambda ? (c) What is the frequency `f` ? (d) What is the amplitude of the magnetic field of the wave (e) write an expression for the magnetic field of the wave. |
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Answer» (a) From the knowledge of wave we can see that electromagnetic wave is travelling along negative y- direction, as `omega t` and ky both are positive. (b) `k=1.8 rad//m` `k = (2pi)/(lambda)` `lambda = (2pi)/k=(2pi)/1.8=3.5 m` (c) `omega =5.4xx10^6 rads//s` `omega=2pif` `f = omega/(2pi)=(5.4xx10^6)/(2pi)` `8.6xx10^5 Hz` (d) `E_0=3.0 N//C` From the relation, `c = (E_0)/(B_0)` We have, `B_0=(E_0)/c=3.0/(3.0xx 10^8)` `=10^8 T` (e) `E` is along hati direction, wave is travelling along negative y-direction. Therefore, oscillations of `B` are along z- direction or `B = (10^-8 T) cos [(1.8 rad//m)y + (5.4 xx 10^6 rad//s)t ] hat k`. |
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