In case of a forced vibration, the resonance wave becomes very sharp when the

Options

A. restroring force is small
B. damping force is small
C. quality factor is small
D. applied periodic force is small.

Explanation

To solve the question regarding the conditions under which the resonance wave becomes very sharp in the case of forced vibrations, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Forced Vibrations**:
- Forced vibrations occur when an external periodic force is applied to a system, causing it to oscillate.

2. **Define Resonance**:
- Resonance is the phenomenon that occurs when the frequency of the applied force matches the natural frequency of the system, leading to maximum amplitude of oscillation.

3. **Identify Factors Affecting Resonance**:
- The sharpness of the resonance peak is influenced by several factors, including:
- Restoring force
- Damping force
- Quality factor
- Applied periodic force

4. **Analyze the Damping Force**:
- Damping force opposes the motion of the oscillating system and dissipates energy. A small damping force means less energy is lost, allowing the system to oscillate more freely.

5. **Quality Factor (Q)**:
- The quality factor is a dimensionless parameter that describes how underdamped an oscillator is. A higher Q indicates lower damping and sharper resonance.

6. **Conclusion**:
- The resonance wave becomes very sharp when the damping force is small. Therefore, the correct answer is that the resonance wave becomes very sharp when the damping force is small.

### Final Answer:
- The resonance wave becomes very sharp when the damping force is small.