Question

In the Young's double slit experiment, if the phase of each light wave coming from the two slits is changed by $\pi$, the fringe pattern will:

• A. remain unchanged
• B. shift downwards by half fringe width
• C. disappear
• D. shift upwards by half fringe width

Answer 1

The correct option is A remain unchanged

If the phase difference of light waves from each slit is changed by $\pi$, the change in the phase difference at points on the screen is either $0,-2\pi or2\pi$. Hence, no change in interference pattern occurs on the screen.