Question

In Young's double slit experiment, the separation between the two slits is $d$ and the wavelength of the light is $\lambda$. The intensity of light falling on slit $1$ is four times the intensity of light falling on slit $2$. Choose the correct choice(s).

• A. If $d=\lambda$, the screen will contain only one maximum
• B. If $\lambda <d<2\lambda$, at least one more maximum (besides the central maximum) will be observed on the screen
• C. If the intensity of light falling on slit $1$ is reduced so that it becomes equal to that of slit $2$, the intensities of the observed dark and bright fringes will increase
• D. If the intensity of light falling on slit $2$ is increased so that it becomes equal to that of slit $1$, the intensities of the observed dark and bright fringes will increase

Answer 1

Answer: (A), (B)

The correct options are
A If $d=\lambda$, the screen will contain only one maximum
B If $\lambda <d<2\lambda$, at least one more maximum (besides the central maximum) will be observed on the screen

$dsin\theta =n\lambda$
as $d=\lambda$
$n=sin\theta$ and maximum value of $n$ is 1 as $sin\theta <=1$
so only 1 maximum is formed
if $\lambda <d<2\lambda$ then at least one more maximum (besides the central maximum) will be observed on the screen
option $A,B$ are correct