Interference was observed in an interference chamber when air was present. Now, the chamber is evacuated and if the same light is used, a careful observation will show

• no interference

• interference with bright band

• interference with dark bands

• interference in which breadth of the fringe will be slightly increased 

What kind of fringes do you expect to observe if white light is used instead of monochromatic light?

Define a wavefront. Using Huygens’ principle, verify the laws of reflection at a plane surface.

In a single slit diffraction experiment, the width of the slit is made double the original width. How does this affect the size and intensity of the central diffraction band ? Explain.

When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the obstacle. Explain why

The refractive index of glass is 1.520 for red light and 1.525 for blue light. Let D₁ and D₂ be an of minimum deviation for red and blue light respectively in a prism of this glass. Then

A Young’s double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is