A coil of wire is arranged with its plane perpendicular to a uniform magnetic field o flux density B. when the radius of the coil increases from r1 to r2 in time Δt then what is the emf induced in the coil ?
Correct answer: C. ωB(r22-r12)/Δt
- A. ωB/r22-r12/Δt
- B. ωB(r2-r1)2/Δt
- C. ωB(r22-r12)/Δt
- D. ωB(r22+r12)/Δt
Explanation
With the coil's plane perpendicular to the field, flux is Bπr². Thus the induced emf magnitude is Bπ(r₂² − r₁²)/Δt, corresponding to option c if the displayed symbol is intended to be π.
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