What creates negative charge on a comb when it's rubbed against hair?

Options

A. Charging by conduction
B. Charging by induction
C. Charging by radiation
D. Charging by friction

Answer

### Step-by-Step Solution:

1. **Understanding Charge**: Every object is made up of atoms, which contain protons (positively charged), neutrons (neutral), and electrons (negatively charged). The balance of these charges determines whether an object is neutral, positively charged, or negatively charged.

2. **Rubbing the Comb Against Hair**: When you rub a plastic comb against your hair, friction occurs between the two surfaces. This friction causes electrons to move from one material to another.

3. **Electron Transfer**: In this case, the hair loses electrons to the comb. Since electrons are negatively charged, when hair loses electrons, it becomes positively charged.

4. **Comb Gains Electrons**: As the comb gains the electrons that the hair has lost, it becomes negatively charged. This is because the comb now has more electrons than protons.

5. **Resulting Charges**: After rubbing, the comb has a negative charge due to the excess electrons, while the hair has a positive charge due to the deficit of electrons.

6. **Conclusion**: The negative charge on the comb is created because it has gained electrons from the hair during the rubbing process.