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Question: Answered & Verified by Expert
A long metal rod of length 'L' completes the circuit as shown. The area of the circuit
is perpendicular to magnetic field ' $B^{\prime}$. Total resistance of the circuit is ' $\mathrm{R}$ '. The force
needed to move the rod in the direction as shown with constant speed ' $V$ ' is
PhysicsMagnetic Effects of CurrentMHT CETMHT CET 2020 (19 Oct Shift 1)
Options:
  • A $\frac{\mathrm{B}^{2} \mathrm{LV}}{\mathrm{R}}$
  • B $\frac{\mathrm{BLV}}{\mathrm{R}}$
  • C $\frac{\mathrm{BLV}^{2}}{\mathrm{R}}$
  • D $\frac{\mathrm{B}^{2} \mathrm{~L}^{2} \mathrm{~V}}{\mathrm{R}}$
Solution:
2420 Upvotes Verified Answer
The correct answer is: $\frac{\mathrm{B}^{2} \mathrm{~L}^{2} \mathrm{~V}}{\mathrm{R}}$
(A)
$\begin{array}{l}
\text { Power } \mathrm{P}=\frac{\mathrm{B}^{2} \mathrm{~L}^{2} \mathrm{~V}^{2}}{\mathrm{R}} \\
\therefore \mathrm{FV}=\frac{\mathrm{B}^{2} \mathrm{~L}^{2} \mathrm{~V}^{2}}{\mathrm{R}} \\
\therefore \mathrm{F} \quad=\frac{\mathrm{B}^{2} \mathrm{~L}^{2} \mathrm{~V}}{\mathrm{R}}
\end{array}$

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