Question

The figure shows a square loop $L$ of side $5cm$ which is connected to a network of resistances.
The whole setup is moving towards right with a constant speed of $1cm{s}^{-1}$. At some instant, a part of $L$ is in a uniform magnetic field of $1T$, perpendicular to the plane of the loop. If the resistance of $L$ is $1.7\Omega$ , the current in the loop at that instant will be close to :

• A. $115\mu A$
• B. $170\mu A$
• C. $60\mu A$
• D. $150\mu A$

Answer 1

Answer: (B)

Since it is a balanced wheatstone bridge, its equivalent resistance $=\frac{4}{3}\Omega$
$\epsilon =B\ell v=5\times 10^{-4}V$
So total resistance
$R=\frac{4}{3}+1.7\approx 3\Omega$
$\therefore i\frac{\epsilon }{R}\approx 166\mu A\approx 170\mu A$