Micrometer Attached to Movable Mirror in Interferometer

[JSGandora]

Homework Statement

A micrometer is connected to the movable mirror of an interferometer. When the micrometer bears on a thin metal foil, the net number of bright fringes that move, compared to the empty micrometer, is 272. What is the thickness of the foil? The wavelength of light used is 589 nm.

I don't understand how to the micrometer is attached and what the metal foil does. Can someone tell me what it means in different words? Thanks.

Homework Equations

Not sure until I figure out what the question is saying.

The Attempt at a Solution

Not sure until I figure out what the question is saying.

 

[anathema]

The interferometer is a scientific instrument used to measure small distances or changes in distance. It works by splitting a beam of light into two and then recombining them. When the two beams are recombined, they interfere with each other and create a pattern of bright and dark fringes. The position of these fringes can be measured and used to determine the distance between the two mirrors.

In this case, the micrometer is a device used to measure very small distances. It is attached to the movable mirror of the interferometer, which means that it can move the mirror by very small increments. The metal foil is placed between the two mirrors, and when the micrometer bears on it, it causes a change in the distance between the two mirrors. This change in distance causes a change in the pattern of fringes, which is what we are measuring.

The question is asking for the thickness of the metal foil, given that the number of bright fringes that move is 272. To solve this, we need to use the equation:

n = 2t/λ

Where:
n = number of fringes
t = thickness of the foil
λ = wavelength of light (in this case, 589 nm)

Rearranging the equation, we get:
t = (nλ)/2

Substituting in the values, we get:
t = (272 x 589 nm)/2 = 160296 nm = 0.160296 μm

Therefore, the thickness of the metal foil is approximately 0.160296 micrometers. I hope this helps clarify the question for you. Let me know if you have any further questions.