The electric field portion of an electromagnetic wave is given by ( all variables in SI units) `E=10^(-4) sin (6xx10^(5)t -0.01x)` The. Frequency (f) and the speed (v) of electromagnetic wave are

Options

A. `f= 30/pi` kHz and `v = 1.5 xx 10^(7) ms^(-1)`
B. `f = 90/pi` kHz and `v = 6.0 xx 10^(7) ms^(-1)`
C. `f = 300/pi` kHz and `v = 6.0 xx 10^(7) ms^(-1)`
D. `f = 600/pi` kHz and `v = 7.5 xx 10^(7) ms^(-1)`

Answer

C

Explanation

`omega = 6 xx 10^(5) = 2pi f`
`f = 6/(2pi) xx 10^(5) = 3/pi xx 10^(5) Hz`
`= 300/pi `kHz
Wave speed `= omega/k`
` = (6 xx 10^(5))/(0.01) = 6 xx 10^(7) m//s`