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A coil carrying a current 'I' has r...

A coil carrying a current 'I' has radius 'r' and number of turns 'n' it is reqound so that radius of the new coil is `(r )/(4)` and it carries current `I' The ratio of the magnetic moment of the new coil to that of the original coil is

A

evr

B

`(evr)/(2)`

C

`(ev)/(2r)`

D

`(vr)/(2e)`

Text Solution

Verified by Experts

The correct Answer is:
C
The length of the coil
`L=n xx 2pi r= n 2pi xx(r )/(4)` ltbnrgt? The magnetic moment of the coil M= nIA
`=4xxpi(r )/(4)^(2)=(4r^(2))/(16r^(2))=1/4`
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