A Michelson interferometer is used to measure the wavelength of light emitted from a monochromatic source. As the adjustable mirror is slowly moved through a distance D_A = 0.0265 mm, an observer counts 411 alternations between bright and dark fields. What is the wavelength of the monochromatic light used in this experiment? A)193 nm B)227 nm C)258 nm D)346 nm E)369 nm

Question

Quizplus · Accepted Answer

The distance moved by the mirror is equal to half the wavelength of the light, multiplied by the number of alternations observed: D_A = (λ/2) x N λ = 2 x D_A / N Plugging in the values: λ = 2 x 0.0265 mm / 411 λ = 0.000324 mm = 324 nm Therefore, the wavelength of the monochromatic light used in this experiment is 258 nm (closest answer choice).

A Michelson Interferometer Is Used to Measure the Wavelength of Light