Question

Two light waves superimposing at the mid - point of the screen are coming from coherent sources of light with phase difference $3\pi$ rad . Their amplitude at the given 1 cm each . The resultant amplitude at the given point will be,

• A. 5m
• B. 3m
• C. 2m
• D. zero

Answer 1

The correct option is D zero

Resultant amplitude,
A= $\sqrt{A_1^2+A_2^2+2A_1{A}_{2}cos\varphi }$
Here, $A_1=A_2=1cm,\varphi =3\pi rad,\varphi =3\pi rad$
$A_R=0$