Question

Two coherent waves of light will not produce constructive interference if the phase difference between them is

• A. $0^0$
• B. ${360}^0$
• C. ${720}^0$
• D. ${90}^0$

Answer 1

The correct option is D ${90}^0$

Constructive interference for coherent waves takes place when phase difference = $2n\pi$ where n is a integer

So the only case in the options when constructive interference will not take place is ${90}^{\circ }$

Answer. D