Phase difference corresponding to a Path Difference of λ/3 is 120°.

Explanation:

The Young's double-slit experiment is a classic experiment that demonstrates the wave nature of light. In this experiment, a beam of light passes through two narrow slits, creating two coherent sources of light. The light waves from these two slits interfere with each other, resulting in an interference pattern on a screen placed behind the slits.

Path Difference and Phase Difference:
When light waves from the two slits reach a point on the screen, they interfere with each other. The path difference is the difference in the distances traveled by the two waves from the slits to that point on the screen. The path difference can be calculated using the formula:

Path Difference = d × sin(θ)

where d is the separation between the slits and θ is the angle between the line joining the point on the screen to the center of the double-slit and the line joining the center of the double-slit to one of the slits.

The phase difference is related to the path difference and the wavelength of light. The phase difference is given by the formula:

Phase Difference = (2π/λ) × Path Difference

where λ is the wavelength of light.

Calculating the Phase Difference:
Given that the path difference is λ/3, we can substitute this value into the formula for phase difference:

Phase Difference = (2π/λ) × (λ/3)

Simplifying the expression:

Phase Difference = (2π/3)

Converting the phase difference into degrees:

Phase Difference = (2π/3) × (180/π)

Phase Difference = 120°

Therefore, the correct answer is option 'D' - 120.