Two vertical metallic plates carrying equal and opposite charges are kept parallel to each other like a parallel plate capacitor. A small spherical metal ball is suspended by a long insulated thread such that it hangs freely in the centre of the two metallic plates. The ball which is uncharged is taken slowly towards the positively charged plate and is made to touch that plate. Then the ball will

Options

A. stick to the positively charged plate
B. come back to its original position and will remain there
C. oscillate between the two plates touching each plate in turn
D. oscillate between the two plates without touching them

Answer

To solve the problem, let's break it down step by step:

### Step 1: Understanding the Setup
We have two vertical metallic plates, one positively charged and the other negatively charged, arranged parallel to each other. A small uncharged spherical metal ball is suspended in the middle of these plates.

**Hint:** Identify the nature of the charges on the plates and the initial condition of the ball.

### Step 2: Bringing the Ball Towards the Positive Plate
When the uncharged ball is brought slowly towards the positively charged plate, it experiences an electric field due to the charged plates. Since the ball is uncharged, it initially has no net charge.

**Hint:** Recall how electric fields affect neutral objects and how induction can occur.

### Step 3: Induction and Charging of the Ball
As the ball approaches the positively charged plate, it becomes polarized due to the electric field. The side of the ball closer to the positive plate will develop a negative charge (due to the attraction of electrons), while the side farther away will develop a positive charge. When the ball touches the positively charged plate, it gains a positive charge.

**Hint:** Think about the process of charging by conduction and how the ball interacts with the plate.

### Step 4: Effects of Gaining Charge
After touching the positive plate, the ball is now positively charged. The negatively charged plate will now exert an attractive force on the positively charged ball, while the positively charged plate will exert a repulsive force.

**Hint:** Consider the forces acting on the ball after it has gained a positive charge.

### Step 5: Motion of the Ball
The ball will be attracted towards the negatively charged plate and will move in that direction. Upon reaching the negatively charged plate, it will touch that plate and gain a negative charge.

**Hint:** Analyze the forces acting on the ball as it moves between the plates.

### Step 6: Oscillation Between the Plates
After gaining a negative charge from the negatively charged plate, the ball will now be repelled by that plate and attracted back towards the positively charged plate. This process will continue, causing the ball to oscillate back and forth between the two plates, touching each plate in turn.

**Hint:** Think about the nature of oscillatory motion and the forces involved.

### Conclusion
The final conclusion is that the ball will oscillate between the two plates, touching each plate in turn.

**Final Answer:** The ball will oscillate between the two plates, touching each plate alternately.

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