Question

Intensity of the central maximum in Youngs double slit experiment is I. When one of the slit is closed the intensity is $I_0$. The ratio $I/I_0$ is........

• A. $2:1$
• B. $1:2$
• C. $4:1$
• D. $1:4$

Answer 1

The correct option is D $1:4$

Intensity is proportional to square of amplitude of wave$.$

If amplitude of wave of each source is a$,$ then after superposition intensity is proportional to $(2a{)}^2$ $i.e.,$ $4a^2.$

If one source is closed$,$ there is no superposition $,$

So$,$ intensity is proportional to $a^2.$

then$,$ $l/4l=1/4=1:4$

Hence,

option $\left(D\right)$ is correct answer.