Question

In a 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)

For d = $\lambda$, there will be only one, central maxima.
For $\lambda < d < 2 \lambda$, there will be three maximas on the screen
corresponding to path difference. $ \Delta x = O$ and $\Delta x = \pm \lambda.$
$\therefore $ Correct options are (a) and (b).