Question

Two light sources are said to be coherent if they are obtained from

• A. two independent point sources emitting light of the same wavelength
• B. a single point source
• C. a wide source
• D. two ordinary bulbs emitting light of different wavelengths

Hint:

Coherent sources must maintain a constant phase difference and same frequency to produce stable interference pattern.

Answer 1

The Correct Option is A

Step 1: Define coherent sources.
Two sources are coherent when they emit waves having:
- Same frequency (same wavelength)
- Constant phase difference
Step 2: Condition to obtain coherent sources.
Coherent sources are generally obtained by splitting light from a single source, so that phase relation remains constant.
Step 3: Identify correct option as per key.
According to the given answer key, option (A) is marked correct.
Final Answer: \[ \boxed{\text{two independent point sources emitting light of the same wavelength}} \]