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The oscillating magnetic field in a plane electromagnetic wave is given by `B_(y)=(8xx10^(-6))sin [2xx10^(11)t+300 pi x ] T` (i) Calculate the wavelength of the electromagnetic wave. (ii) Write down the expression for the oscillating electric field. |
Answer» Given equation is `B_(y)=(8xx10^(-6))sin [2xx10^(11)t+300 pi x]T` Comparing the given equation with the equation of magnetic field varying sinusoidally with x and t `B_(y)=B_(0)sin ((2pi x)/(lambda)+(2pi t)/(T))` We get, `(2 pi)/(lambda)=300 pi :. lambda=(2)/(300)=0.0067 m. and B_(0)=8xx10^(-6)T` (i) Wavelength of the electromagnetic wave `lambda=0.0067m ` or 0.67 cm (ii)`E_(0)=CB_(0)=3xx10^(8)xx8xx10^(-6)=24xx10^(2)=2400 Vm^(-1)` `:.` The required expression for the oscillating electric field is `E_(z)=E_(0) sin ((2 pi x)/(lambda)+(2pi t)/(T))=2400 sin (300 pi x + 2 xx 10^(11)t)` v/m. |
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