Read the following text and answer the following questions on the basis of the same:
Electromagnetic damping: Take two hollow thin cylindrical pipes of equal internal diameters made of aluminium and PVC, respectively. Fix them vertically with clamps on retort stands.
Take a small cylindrical magnet having diameter slightly smaller than the inner diameter of the pipes and drop it through each pipe in such a way that the magnet does not touch the sides of the pipes during its fall. You will observe that the magnet dropped through the PVC pipe takes the same time to come out of the pipe as it would take when dropped through the same height without the pipe. Now instead of PVC pipe use an aluminium pipe. Note the time it takes to come out of the pipe in each case. You will see that the magnet takes much longer time in the case of aluminium pipe. Why is it so? It is due to the eddy currents that are generated in the aluminium pipe which oppose the change in magnetic flux, i.e., the motion of the magnet.
The retarding force due to the eddy currents inhibits the motion of the magnet. Such phenomena are referred to as electromagnetic damping Note that eddy currents are not generated in PVC pipe as its material is an insulator whereas aluminium is a conductor. This effect was discovered by physicist Foucault (1819-1868).
To observe electromagnetic damping a magnet should be dropped through a metal pipe and:

Options

A. the magnet should not touch inner wall of the pipe.
B. the magnet should touch the inner wall of the pipe.
C. it does not matter whether the magnet touches the inner wall of the pipe or not.
D. the magnet should be larger in size than the diameter of the pipe.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Experiment:**
- We have two hollow cylindrical pipes made of different materials: one is aluminum (a conductor) and the other is PVC (an insulator).
- A small cylindrical magnet is dropped through each pipe, ensuring it does not touch the sides.

2. **Observations with PVC Pipe:**
- When the magnet is dropped through the PVC pipe, it takes the same time to exit as it would if dropped from the same height without the pipe.
- This indicates that the PVC pipe does not affect the motion of the magnet since it does not conduct electricity and therefore does not generate eddy currents.

3. **Observations with Aluminum Pipe:**
- When the magnet is dropped through the aluminum pipe, it takes a longer time to exit compared to the PVC pipe.
- This is due to the generation of eddy currents in the aluminum pipe as the magnet falls. Eddy currents are loops of electric current induced within conductors by a changing magnetic field.

4. **Explanation of Eddy Currents:**
- As the magnet falls, it creates a changing magnetic field in the aluminum pipe, which induces eddy currents.
- These eddy currents produce their own magnetic field that opposes the motion of the magnet (according to Lenz's Law), resulting in a retarding force that slows down the magnet.

5. **Conclusion:**
- The phenomenon observed when the magnet takes longer to fall through the aluminum pipe is known as electromagnetic damping.
- This effect is not observed in the PVC pipe because it does not conduct electricity and thus does not generate eddy currents.

6. **Final Answer to the Question:**
- To observe electromagnetic damping, a magnet should be dropped through a metal pipe (like aluminum) and it should not touch the inner wall of the pipe during its fall.

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