Physics

Problem

An electromagnetic wave is given by

E(x,t)=40\,\sin\bigl(2\pi\times10^{7}t-0.21\pi x\bigr)\;\text{V m}^{-1},

with

x

in metres and

t

in seconds. Solve the following: a. (i) State the direction of propagation of the wave and calculate its speed. b. (ii) Compute the phase difference between points

A(1.2\,\text{m})

and

B(3.6\,\text{m})

at the instant

t=0

. c. (iii) What is the earliest time after

t=0

at which the electric field at point

A

attains its maximum positive value? Show all working clearly.

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