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Electric Charges And Fields

Question
CBSEENPH12040024
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The electric field part of an electromagnetic wave in a medium is represented by
Ex = 0;
straight E subscript straight y space equals open square brackets space 2.5 space straight N over straight C space cos space left square bracket space left parenthesis space 2 straight pi space straight x space 10 to the power of 6 space rad over straight m right parenthesis straight t space minus open parentheses straight pi space straight x space 10 to the power of negative 2 end exponent rad over straight s close parentheses straight x close square brackets straight E subscript straight s space equals space 0. space The space wave space is

  • moving along y direction with frequency 2π x 106 Hz and wavelength 200 m.

  • moving along x direction with frequency 106 Hz and wavelength 200 m.

  • moving along x direction with frequency 106 Hz and wavelength 200 m

  • moving along x- direction with frequency 106 Hz and wavelength 200 m

Solution

C.

moving along x direction with frequency 106 Hz and wavelength 200 m

Comparing the given equation
straight E subscript straight y space equals open square brackets space 2.5 space straight N over straight C space cos space left square bracket space left parenthesis space 2 straight pi space straight x space 10 to the power of 6 space rad over straight m right parenthesis straight t space minus open parentheses straight pi space straight x space 10 to the power of negative 2 end exponent rad over straight s close parentheses straight x close square brackets With space the space standard space equation straight E subscript straight y space equals space straight E subscript 0 space cos space left parenthesis ωt minus kx right parenthesis we space get straight omega space equals space 2 πf space equals space 2 straight pi space straight x space 10 to the power of 6 straight f space equals space 10 to the power of 6 space Hz Moreover comma space we space know space that fraction numerator 2 straight pi over denominator straight lambda end fraction space equals space straight k space equals space straight pi space straight x space 10 to the power of negative 2 end exponent space straight m to the power of negative 1 end exponent straight lambda space equals space 200 space straight m
Hence, the wave is moving along positive x -direction with frequency 106 Hz and wavelength 200 m.

Some More Questions From Electric Charges and Fields Chapter

a) An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why not?
b) Explain why two field lines never cross each other at any point? 

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