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An iron core supports N turns. If a curr...

An iron core supports N turns. If a current `i` produces a magnetic flux across the Core's cross section equal to `phi` , then the magnetic field energy is _______ .

A

N i` phi`

B

`(1)/(2) N phi i`

C

`N^(2) iphi`

D

`N i^(2) phi`

Text Solution

Verified by Experts

The correct Answer is:
B
Self -inductance of toroid
`L = N (phi)/(i)`
Energy of toroid `E=(1)/(2)Li^(2)= (1)/(2)((N phi)/(i))i^(2)`
`=(1)/(2)N phi i`
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