Question

If the movable mirror in a michelson interferometer is moved 120 microns, how many fringes would be counted for 600 nm light? group of answer choices

O 100
O 720
O 200
O 300
O 400

Answer 1

To find out how many fringes are counted when a Michelson interferometer's movable mirror is moved 120 microns, we use the formula involving the mirror movement and the light wavelength, which gives us 400 fringes.

Step-by-step explanation:

The question revolves around determining the number of interference fringes observed when the movable mirror in a Michelson interferometer is moved a certain distance. To calculate this we need to know that for each wavelength (λ) shift in path difference, caused by moving the mirror, we observe one fringe change. The total change in optical path length is twice the physical distance the mirror is moved, due to the round trip of light.

Here, the movable mirror is moved by 120 microns, which is 120 × 10-6 meters, and the wavelength of light used (λ) is 600 nm, which is 600 × 10-9 meters.

Using the formula:

Fringe count = (2 × Mirror movement) / Wavelength

Number of fringes = (2 × 120 × 10-6m) / (600 × 10-9m) = 400 fringes