Question

First, you must find the wavelength of the laser. You shine the laser into the interferometer and then move one of the mirrors until you have counted 100.0 fringes passing the crosshairs of the telescope. The extremely accurate micrometer shows that you have moved the mirror by 0.03164 millimeters. What is the wavelength λ of the laser?

Answer 1

316.4 nm

Step-by-step explanation:

wavelength λ of the laser = (the absolute value of the difference between the initial position and final position after the mirror has been moved ) / 100.0 fringes = 0.03164 mm ÷ 1000 = 0.00003164 m / 100 = 0.0000003164 m = 316.4 nm

Answer 2

632.8 nm

Step-by-step explanation:

CORRECT WAY TO SOLVE:

The equation for how far the mirror has moved:

2y=mλ

y is how far the mirror has moved

m is how many fringes have passed the crosshairs

λ is the wavelength (what we are finding)

Plugging in, we get

2 * 0.03164 [mm] = 100λ

2 * 0.03164 [mm] / 100 = λ

0.0006328 [mm] = λ

Convert to nm: 0.06328 [mm] * 10^6 [nm/mm] = 632.8 [nm]

Note that you MUST multiply the mirror displacement by 2