Why is a lightning conductor installed on a building?
A lightning conductor, also known as a lightning rod or a lightning protection system, is installed on buildings to protect them from the destructive effects of lightning strikes. Lightning is a discharge of electricity that occurs during storms, and it can cause significant damage to structures and harm to the people inside them. To prevent this, lightning conductors are strategically placed on buildings to provide a safe path for the lightning to follow and direct the electrical charge harmlessly into the ground. The correct answer to the question is option 'D' - a lightning conductor is installed on a building so that it conducts electric charge to the ground when lightning strikes the building.

Explanation:
1. What is a lightning conductor?
- A lightning conductor is a metal rod or system of rods that is mounted on the roof or the highest point of a building.
- It is designed to attract lightning strikes and provide a path of least resistance for the electrical current to follow.
- The conductor is typically made of a highly conductive material such as copper or aluminum, which allows the electrical charge to flow easily.

2. How does a lightning conductor work?
- When a lightning strike occurs, the lightning conductor acts as a preferred pathway for the electrical discharge.
- The pointed tip of the conductor helps to attract the lightning by creating a strong electric field.
- The conductor is connected to a network of metal cables and conductive materials that are buried in the ground.
- These cables, known as down conductors, provide a direct path for the electrical charge to flow from the lightning conductor to the ground.
- The conductive materials in the ground, such as copper or aluminum rods, disperse the electrical energy into the earth, where it can safely dissipate.

3. What is the purpose of a lightning conductor?
- The main purpose of a lightning conductor is to protect buildings and the people inside them from the destructive effects of lightning strikes.
- When lightning strikes a building without a lightning conductor, it can cause fires, explosions, structural damage, and even electric shocks.
- By providing a safe path for the electrical charge to follow, a lightning conductor helps to prevent these damages.
- It directs the lightning's electrical energy away from the building, reducing the risk of fire and structural damage.
- It also minimizes the likelihood of electric shocks to people inside the building by safely conducting the electrical charge into the ground.

In conclusion, a lightning conductor is installed on a building to protect it from the damaging effects of lightning strikes. It achieves this by providing a safe pathway for the electrical charge to follow, directing it harmlessly into the ground.