Statement-1: When light reflects from the air-glass plate interface, the reflected wave suffers a phase change of `pi`.
Statement-2: The centre of the interference pattern is dark

Options

A. Statement-1 is true, statement-2 is true: Statement-2 is a correct explanation for statement-1
B. statement-1 is false, statement-2 is true
C. Statement-1 is true, Statement-2 is false.
D. statement-1 is true, statement-2 is true and statement-2 is not the correct explanation of statement-1

Answer

A

Explanation

`I_(max)=(sqrt(I)+sqrt(4I))^(2)=9I=I_(m)impliesI=(I_(m))/(9)`
`I_(P)=I+4I+2sqrt((I)(4I))cosphi`
`=5I+4Icosphi`
`=I+4I(1+cosphi)`
`=I+8Icos^(2)((phi)/(2))`
`=(I_(m))/(9)(1+8cos^(2)((phi)/(2))`