The pole piece of a horse shoe magnet are made cylindrical so that the deflection of the

Options

A. both bodies come to rest
B. both bodies move after collision
C. the moving body stops and body at reat starts moving
D. the stationary body remains stationary and the moving body rebounds

Explanation

To solve the question regarding the cylindrical pole pieces of a horseshoe magnet and their effect on the deflection in a galvanometer, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**: The question refers to a horseshoe magnet with cylindrical pole pieces. The purpose of these pole pieces is to create a magnetic field that interacts with a current-carrying coil, typically found in devices like galvanometers.

2. **Deflection in a Galvanometer**: The deflection (θ) in a galvanometer is related to the current (I) flowing through the coil. The relationship can be expressed as:
\[ I = k \cdot \tan(\theta) \]
where \( k \) is a constant known as the reduction factor of the galvanometer.

3. **Proportionality**: From the equation, we can deduce that the deflection θ is directly proportional to the current I. This means that as the current increases, the deflection of the galvanometer needle also increases.

4. **Role of the Cylindrical Pole Pieces**: The cylindrical shape of the pole pieces is designed to create a uniform magnetic field. A uniform magnetic field is crucial for accurate and consistent measurements in a galvanometer. This uniformity ensures that the deflection is solely dependent on the current and not influenced by variations in the magnetic field.

5. **Conclusion**: Therefore, the complete statement can be formulated as:
"The pole pieces of a horseshoe magnet are made cylindrical so that the deflection of the galvanometer is directly proportional to the current flowing through the coil."

### Final Answer:
The pole pieces of a horseshoe magnet are made cylindrical so that the deflection of the galvanometer is directly proportional to the current flowing through the coil.