If two light waves of same amplitude 'a' trvaelling thrugh a mdedium arrive t a point in same pahses then the resultant amplitude r at that points is

Options

A. `R=4a`
B. `R=a`
C. `R=3a`
D. `R=2a`

Answer

D

Explanation

`a_(1)=a_(2)= and alpha_(1) -alpha_(1)0, R=?`
`R= sqrt(a_(1)^(2)+a_(2)^(2)+2a_(1) cos (alpha_(1)-alpha_(2)))`
`=sqrt(a^(2)+a^(2)+ 2aa cos 0)`
`R= 2a`