A circular loop expands such that its radius varies with time according to

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

R(t) = 0.050\,\text{m} + 2.0\times10^{-3}t

, where

t

is in seconds. The loop is placed coaxially in a non-uniform magnetic field described by

B(r) = 0.40\,r\,\text{T\,m}^{-1}

, where

r

is the distance from the centre in metres. Find the magnitude of the emf induced in the loop at

t = 10\,\text{s}

. (a)

3.7\times10^{-5}\,\text{V}

(b)

7.9\times10^{-6}\,\text{V}

(c)

2.5\times10^{-5}\,\text{V}

(d)

1.2\times10^{-5}\,\text{V}