A plane electromagnetic wave in vacuum is described by E(x,t)=100 , (20 x-6 10^ 9 t )…

PHYSICS · Single correct · CBSE · Physics · Electromagnetic Waves · Electromagnetic Waves

Problem

A plane electromagnetic wave in vacuum is described by

E(x,t)=100\,\sin\bigl(20\pi x-6\times10^{9}\pi t\bigr)\;\text{V\,m}^{-1},

where

x

is in metres and

t

in seconds. Find the instantaneous electric field at

x = 0.025\,\text{m}

and

t = 5.0\times10^{-10}\,\text{s}

. (a)

+100\,\text{V\,m}^{-1}

(b)

-100\,\text{V\,m}^{-1}

(c)

0\,\text{V\,m}^{-1}

(d)

-60\,\text{V\,m}^{-1}