A circular loop of radius 0.3 cm lies parallel to amuch bigger circular loop of radius 20 cm. The centre of the small loop is on the axis of the bigger loop. The distance between their centres is 15 cm. If a current of 2.0 A flows through the smaller loop, then the flux linked with bigger loop is

Options

A. `6 xx 10^(-11) "weber"`
B. `3.3 xx 10^(-11) "weber"`
C. `6.6 xx 10^(-9) "weber"`
D. `9.1 xx 10^(-11) "weber"`

Answer

D

Explanation

Let `M_(12)` be the coefficient of mutual induction between loops

`phi_(1) = M_(12)i_(12)`
`rArr (mu_(0)i_(2)R^(2))/(2(d^(2) + R^(2))^(3//2))pi r^(2) = M_(12)i_(12)`
`rArr M_(12) = (mu_(0)R^(2) pi r^(2))/(2(d^(2)+R^(2))^(3//2))`
`phi_(2) = M_(12) i_(1) rArr phi_(2) = 9.1 xx 10^(-11) "weber"`