A monochromatic point source S is placed at a distance of 20 cm from a convex lens (focal length 10 cm) cut into two halves each of which is displaced by 0.5 mm. A screen at O is normal to ${\mathrm{S}}_0$ .




If the gap between the two halves ${\mathrm{P}}_1$ and ${\mathrm{P}}_2$ is decreased, then the fringe width will

Using monochromatic light of wavelength $\lambda$, an experimentalist sets up the Young's double slit experiment in three ways as shown.
If she observes that $y={\beta }^{\prime }$, the wavelength of light used is :

 

A parallel beam of light is incident on a tank filled with water up to a height of $61.5 \mathrm{mm}$ as shown in the figure below. Ultrasonic waves of frequency $0.5 \mathrm{MHz}$ are sent along the length of the water column using a transducer placed at the top, and they form longitudinal standing waves in the water. Which of the schematic plots below best describes the intensity distribution of the light as seen on the screen? Take the speed of sound in water to be $1,500 \mathrm{m} {\mathrm{s}}^{-1}$.