Wave optics

Ans 1


@RIDDHISHAH couldn't understand why x+3lamda/2
Pls explain this part

@SiddharthaGhosh when x is zero the path difference is 2 lambda. You can see that as x increases difference decreases. For minimum intensity path difference must be (2n+1)lambda/2. After 2 lambda the nearest one will be 3 lambda/2