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

Options

A. Restoring force is small
B. damping force is small
C. quality factor is small
D. quality factor is small

Explanation

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

### Step 1: Understand the Concept of Resonance
In forced vibrations, resonance occurs when the frequency of the external force matches the natural frequency of the system. This leads to a significant increase in amplitude.

**Hint:** Recall that resonance is a phenomenon that occurs when an external force matches the natural frequency of a system.

### Step 2: Identify Factors Affecting Resonance
The sharpness of the resonance wave is influenced by the damping present in the system. Damping refers to the forces that oppose the motion of the vibrating system, which can reduce the amplitude of oscillations over time.

**Hint:** Consider how damping affects the energy of the system and the amplitude of vibrations.

### Step 3: Analyze the Options Given
The options provided are:
1. Restoring force is small
2. Damping force is small
3. Quality factor is small
4. Quality factor is large

Among these, the damping force is crucial in determining the sharpness of the resonance. A small damping force leads to a sharper resonance peak.

**Hint:** Think about how damping influences the amplitude and width of the resonance peak.

### Step 4: Conclusion
The resonance wave becomes very sharp when the damping force is small. This is because less damping means that the system can oscillate more freely, resulting in a sharper peak in the resonance curve.

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