A coil with a number of turns N, is made from a wire of length L, carrying current I. What will be the magnetic moment of the coil?
Correct answer: C. L2 I / 4πN
- A. L2 I / 4π N2
- B. L2NI / 4π
- C. L2 I / 4πN
- D. L2IN2 / 4π
Explanation
The magnetic moment (M) of a coil is given by M = NIA, where A is the area of one turn. For a wire of length L bent into N turns, the radius of each turn is r = L / 2πN, makig the area A=πr2 =L2/ 4πN2.Thus, M=NI(L2 /4πN2) =L2I/4πN2.
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