Question

The phase difference between the two superimposing waves that give rise to a bright spot in a Young’s double-slit experiment is (n is an integer) ______.

Options

• 2nπ

• `2nπ + π/4`

• `2nπ + π/2`

• 2nπ + π

Answer 1

The phase difference between the two superimposing waves that give rise to a bright spot in a Young’s double-slit experiment is (n is an integer) 2nπ.

Explanation:

In Young’s double-slit experiment (YDSE), bright fringes are formed due to constructive interference.

For constructive interference:

Path difference (∆) = nλ

Where n is an integer.

The relation between phase difference ϕ and path difference ∆x is:

ϕ = `(2pi)/λ  ∆x`

ϕ = `(2pi)/λ  .  nλ   ...(∴ ∆x = nλ)`

= 2nπ

Thus, the phase difference for a bright spot must be an integral multiple of 2π.