A glass rod rubbed with silk is used to charge a gold leaf electroscope and the leaves are observed to diverge. The electroscope thus charged is exposed to `X`-rays for a short period. Then

Options

A. Further dilate
B. Start oscillating
C. Collapse
D. Remain unaltered

Answer

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

### Step 1: Charging the Glass Rod
When a glass rod is rubbed with silk, electrons are transferred from the glass rod to the silk. This results in:
- The glass rod becoming positively charged (due to a deficiency of electrons).
- The silk becoming negatively charged (due to an excess of electrons).

**Hint:** Remember that rubbing two materials can lead to the transfer of electrons, resulting in one material becoming positively charged and the other negatively charged.

### Step 2: Charging the Electroscope
When the positively charged glass rod is brought near the metal knob of the gold leaf electroscope, the following occurs:
- The positive charge of the glass rod induces a separation of charges in the electroscope. Electrons from the ground (or the base of the electroscope) move up to the knob to neutralize some of the positive charge.
- This causes the gold leaves to acquire a positive charge (since they lose some electrons) and they start to diverge due to the repulsion between like charges.

**Hint:** Understand the concept of charge induction, where a charged object can cause the redistribution of charges in a neutral conductor.

### Step 3: Exposure to X-rays
When the charged electroscope is exposed to X-rays, which are a form of ionizing radiation, the following happens:
- X-rays can ionize the air around the electroscope, creating free electrons and positive ions.
- The free electrons can neutralize some of the positive charge on the electroscope, leading to a reduction in the overall charge.

**Hint:** Ionizing radiation can produce free charges, which can neutralize existing charges in a conductor.

### Step 4: Observing the Effect
As a result of the exposure to X-rays, the electroscope will lose some of its positive charge. Consequently:
- The divergence of the gold leaves will decrease as they become less positively charged and may even collapse back together if enough charge is neutralized.

**Hint:** Consider how the balance of charges affects the behavior of the electroscope leaves.

### Conclusion
Thus, after the electroscope is exposed to X-rays, the leaves will collapse back together due to the reduction in positive charge.

**Final Answer:** The leaves of the electroscope will collapse after exposure to X-rays.