A bar magnet is placed upright on a floor (so that the axis of the magnet is vertical). A copper ring is held above the magnet, with its plane horizontal, and released. The copper ring falls in such a manner that its axis always coincides with that of the magnet. What will be the acceleration with which the ring will fall ? Acceleration due to gravity is 10 `m//s^(2)`

Options

A. `10m//s^(2)`
B. Less than `10m//s^(2)`
C. More than `10m//s^(2)`
D. The answer will depend upon which pole of the magnet is up

Explanation

To solve the problem, we need to analyze the situation step by step:

### Step 1: Understanding the setup
A bar magnet is placed upright on the floor, and a copper ring is held above it. The ring is released and falls straight down, maintaining its axis aligned with that of the magnet.

**Hint:** Visualize the setup to understand the interaction between the magnet and the falling ring.

### Step 2: Magnetic Flux and Induction
As the copper ring falls towards the magnet, it enters a region of changing magnetic flux. The magnetic field lines from the magnet are increasing through the area of the ring as it approaches the magnet. According to Faraday's law of electromagnetic induction, a change in magnetic flux through the ring induces an electromotive force (EMF).

**Hint:** Recall Faraday's law and how it relates to changing magnetic fields and induced EMF.

### Step 3: Induced Current and Lenz's Law
The induced EMF generates a current in the copper ring. According to Lenz's law, the direction of the induced current will be such that it opposes the change in magnetic flux. As the ring falls, the induced current will create its own magnetic field that opposes the magnetic field of the bar magnet.

**Hint:** Remember that Lenz's law states that induced currents oppose the change that creates them.

### Step 4: Forces Acting on the Ring
While the ring falls, two main forces act on it:
1. The gravitational force acting downward (weight of the ring).
2. The magnetic force due to the induced current, which acts upward (opposing the fall).

Since the induced magnetic force opposes the gravitational force, the net force acting on the ring will be less than the gravitational force.

**Hint:** Consider the balance of forces acting on the ring to determine the net effect on its motion.

### Step 5: Conclusion on Acceleration
Since the upward magnetic force opposes the downward gravitational force, the net acceleration of the ring will be less than the acceleration due to gravity (10 m/s²). Thus, the ring will fall with an acceleration that is less than 10 m/s².

**Final Answer:** The acceleration with which the ring will fall is less than 10 m/s².