Two sources of sound are in resonance when

Options

A. they look like
B. they are situated at a particular distance from each other
C. they produce the sound of same frequency
D. they are excited by the same excittng device

Explanation

To determine when two sources of sound are in resonance, we can analyze the options provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding Resonance**:
- Resonance occurs when two systems oscillate at the same frequency, leading to an increase in amplitude of the oscillations.

2. **Analyzing the Options**:
- **Option 1**: They look alike.
- This option is irrelevant to the concept of resonance. The appearance of the sources does not affect their ability to resonate.
- **Option 2**: They are situated at a particular distance from each other.
- While distance can affect the intensity of sound, it does not determine resonance. Resonance is about frequency, not distance.
- **Option 3**: They produce the same frequency.
- This option is correct. For two sound sources to be in resonance, they must produce sound waves of the same frequency. This is the fundamental requirement for resonance.
- **Option 4**: They are excited by the same exciting device.
- This option is also not necessarily true. While they can be excited by the same device, it is not a requirement for resonance. The key factor is the frequency of the sound produced.

3. **Conclusion**:
- The correct answer is **Option 3: They produce the same frequency**. This is the condition for two sound sources to be in resonance.

### Final Answer:
Two sources of sound are in resonance when they produce the same frequency.

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