When a plastic comb is passed through dry hair, the charge acquired by the comb is

Options

A. always negative
B. always positive
C. sometimes negative
D. none of the above

Explanation

**Step-by-Step Solution:**

1. **Understanding the Scenario**: We have a plastic comb that is rubbed against dry hair. This action will lead to a transfer of charges due to friction.

2. **Identifying the Charges**: When two different materials are rubbed together, one material tends to lose electrons and becomes positively charged, while the other gains those electrons and becomes negatively charged.

3. **Charge Transfer Process**: In this case, when the plastic comb is rubbed against dry hair, electrons from the hair are transferred to the comb. This is due to the difference in their electron affinity.

4. **Resulting Charge on the Comb**: Since the comb gains electrons, it becomes negatively charged. Conversely, the hair loses electrons and becomes positively charged.

5. **Conclusion**: Therefore, after rubbing the plastic comb on dry hair, the charge acquired by the comb is negative.

**Final Answer**: The charge acquired by the comb is negative.

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