Question

The diagram below shows two identical filament lamps separated by a small distance. Light from the lamps is incident on a narrow slit behind a green filter. The slit is parallel to the filament of each lamp. A photograph is taken of the lamps through the slit. The images of the filament on the photograph are just resolved. The green filter is replaced by a red filter and then by a violet filter. For each filter a photograph is taken of the lamps through the slit. Which of the following correctly describes the resolution of the images using a red and using a violet filter?

Answer 1

when angular separation is $\frac{1.22\lambda}{d}$ points are said to be resolved.

here $\lambda$ is wavelength of light.

filaments are just resolved for green light.

Hence they will be resolved for Red light (wavelength for red light is more than wavelength for green light)

and they will not be resolved for violet light (wavelength for green light is more than wavelength for violet light)

answer is B

Answer 2

The lamps will not be resolved for red light but will be resolved for blue light. Because Resolving power is proportional to 1/wavelength