Q152 / 155 · WBJEE 2022 · Physics

Figure
As shown in figure, a rectangular loop of length ' a' and width ' $b$ ' and made of a conducting material of uniform crosssection is kept in a horizontal plane where a uniform magnetic field of intensity $B$ is acting vertically downward. Resistance per unit length of the loop is $\lambda \Omega / \mathrm{m}$. If the loop is pulled with uniform velocity ' $v$ ' in horizontal direction, which of the following statement is / are true?

  • Correct answer
    A
    Current in the loop $\mathrm{I}=\frac{\mathrm{Bbv}}{\lambda(2 \mathrm{~b}+2 \mathrm{a})}$
  • B
    Current will be in clockwise direction, looking from the top.
  • C
    $V_P-V_S=V_Q-V_R$, where $V$ is the potential
  • Correct answer
    D
    There cannot be any induction in part SR.

Solution

Figure
$\varepsilon=B \times b \times v$ $\mathrm{i}=\frac{\varepsilon}{\mathrm{R}_{\text {total }}}=\frac{\varepsilon}{\lambda(2 \mathrm{~b}+2 \mathrm{a})}$ Current is anticlockwise $$ V_P-V_S \neq V_Q-V_R $$ Also SR, $\vec{\ell} \| \vec{v} ;$ So $\varepsilon=0$

Hence, the correct answer is options: 'A', 'D'.

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