Question

A wire is bent to form the double loop shown in the figure.

There is a uniform magnetic field directed into the plane of the loop. If the magnitude of this field is decreasing, the current will flow from

• A. $\mathrm{a}$ to $\mathrm{b}$ and $\mathrm{c}$ to $\mathrm{d}$
• B. $\mathrm{b}$ to $\mathrm{a}$ and $\mathrm{d}$ to $\mathrm{c}$
• C. $\mathrm{a}$ to $\mathrm{b}$ and $\mathrm{d}$ to $\mathrm{c}$
• D. $\mathrm{b}$ to $\mathrm{a}$ and $\mathrm{c}$ to $\mathrm{d}$

Answer 1

The correct option is C

$\mathrm{a}$ to $\mathrm{b}$ and $\mathrm{d}$ to $\mathrm{c}$

The explanation for the correct option:

In the case of option (C):

1. Lenz's law, an induced electric current flows in the opposite direction as the change that caused it.
2. According to Lenz's law, an emf will be induced in the double loop as the magnetic field's strength decreases.
3. The right-hand thumb rule can be used to determine this current direction.
4. The direction of the flow of current may be determined by placing the thumb of the right hand in the magnetic field and the other fingers in the opposite direction.
5. According to Lenz's law, the induced current flows in a clockwise direction because the induced current is flowing inward while the magnetic field is decreasing.
6. Since the area of the outer loop is larger than the inner loop, the current flows clockwise there and anticlockwise there.

Hence, the current will flow from $\mathrm{a}\mathrm{to}\mathrm{b}\mathrm{and}\mathrm{from}\mathrm{d}\mathrm{to}\mathrm{c}$.

Therefore, option C is the correct answer.