Question

Two conducting wire loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increasing with time. The induced current in the inner loop is

• A. clockwise
• B. anticlockwise
• C. in a direction which depends on the ratio of the loop radii.
• D. zero

Hint:

Lenz's law is all about maintaining the status quo! If the surrounding field increases, the system fights back by creating an opposite field. An increasing **clockwise** external current will always induce an opposing **anticlockwise** counter-current!

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
We are given two concentric, coplanar conducting loops. The outer loop carries a clockwise current that is steadily increasing over time. We need to determine the directional behavior of the induced current set up in the inner loop.

Step 2: Detailed Explanation:
Let's track the magnetic interactions using electromagnetic principles step by step:

• Right-Hand Rule for Magnetic Field: According to the right-hand rule, a clockwise current circulating in the outer loop generates a magnetic field vector ($\vec{B}$) pointing directly inward, perpendicular to the plane of the page, inside the loop's interior region.

• Flux Trends: Since the outer current is explicitly stated to be increasing with time, the downward inward magnetic flux passing through the enclosed area of the inner loop is also increasing over time.

• Lenz's Law Application: Lenz's law dictates that an induced current will always flow in a direction that opposes the net change in magnetic flux that creates it. To oppose an increasing inward magnetic field, the inner loop must generate its own opposing magnetic field pointing directly outward, perpendicular to the plane of the page.

• Induced Current Direction: Applying the right-hand rule in reverse, to produce an outward-pointing magnetic field, the induced current inside the inner loop must circulate in an anticlockwise direction.


Step 3: Final Answer:
The induced current in the inner loop is anticlockwise, which corresponds to option (B).