Van de Graaff generator is

Options

A. The phenomenon of corona discharge
B. The property of hollow conductor is transferred to outer surface
C. Fact that conductor can conduct heat and electricity
D. Both (1) and (2)

Answer

### Step-by-Step Solution

1. **Understanding the Van de Graaff Generator**:
- A Van de Graaff generator is an electrostatic generator that accumulates electric charge on a hollow metal structure, typically shaped like a globe at the top of an insulating column.

2. **Operation Mechanism**:
- The generator uses a moving belt made of insulating material. This belt is wound around two pulleys, one at ground level and the other at the center of the globe.
- As the belt moves, it carries positive charges from the ground to the top of the generator.

3. **Charge Accumulation**:
- At the top of the generator, a carbon brush transfers the positive charge from the belt to the hollow metal globe.
- Over time, this process results in the accumulation of a very high electric potential, often in the range of several million volts.

4. **Electric Field Generation**:
- The high electric potential creates a large electric field around the generator, which can be used to accelerate charged particles.

5. **Understanding Corona Discharge**:
- When the electric field near a pointed conductor (like the one at the top of the Van de Graaff generator) becomes very high, it can ionize air molecules, leading to a phenomenon known as corona discharge.
- This results in a glow due to the recombination of free electrons and ionized air molecules.

6. **Properties of Hollow Conductors**:
- According to the principles governing hollow conductors, any charge supplied to a hollow conductor is distributed uniformly over its outer surface, regardless of the potential increase.

7. **Evaluating Options**:
- **Option A**: Correct, as the operation involves the phenomenon of corona discharge.
- **Option B**: Correct, as it describes the property of hollow conductors.
- **Option C**: Incorrect, as it states a general property of conductors, which is not specific to the Van de Graaff generator.
- **Option D**: Since both A and B are correct, this option is also correct.

8. **Final Conclusion**:
- The correct answer is **Option D**, which states that both options A and B are correct.