A lightning conductor installed in a building

Options

A. does not allow the lightning to fall on the building
B. repels the lightning
C. forces the lightning to fall in an area where there is no building
D. Conducts electric charge to the ground when lightning strikes the building.

Explanation

### Step-by-Step Solution:

1. **Understanding the Purpose of a Lightning Conductor**:
- A lightning conductor is a metal rod installed on top of a building to protect it from lightning strikes. Its primary function is to provide a safe path for the electrical discharge from lightning to reach the ground.

2. **Connection to the Earth**:
- The lightning conductor is connected to the ground through a wire. This connection is crucial because it allows the excess electrical charge from a lightning strike to be safely dissipated into the earth.

3. **Mechanism During a Lightning Strike**:
- When lightning strikes a building, the lightning conductor attracts the electrical discharge. Instead of the lightning hitting the building directly, it strikes the conductor.

4. **Dissipation of Charge**:
- Once the lightning strikes the conductor, the electrical charge travels down through the conductor and into the ground. The earth can absorb a large amount of electrical charge, which helps to prevent damage to the building.

5. **Conclusion**:
- Therefore, the function of a lightning conductor is to conduct electric charge to the ground when lightning strikes the building, thereby protecting the structure from potential damage.

### Final Answer:
The correct option is: **Option 4 - conducts electric charge to the ground when lightning strikes the building.**

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