Question

Which one of the following statements is correct?

• A. Monochromatic light is never coherent
• B. Monochromatic light is always coherent
• C. Two independent monochromatic sources are coherent
• D. Coherent light is sometimes monochromatic
• E. Coherent light is always monochromatic

Answer 1

Answer: (E)

The two sources of same frequency which emits waves with phase difference not changing with time, are called the coherent sources.
Two independent light sources are never coherent. Coherent light is always monochromatic.