Question

In the physics we have Helium-Neon lasers that produce a wavelength of 632 nm. Suppose that we have a diffraction grating that is unlabeled (so we don’t know its slit spacing) and a violet laser pointer whose wavelength we wish to determine. We then shine the Helium-Neon laser on the grating, project the diffraction pattern onto a screen that is 1.00 m from the grating and measure the positions of the diffraction maxima on the screen. Next we remove the Helium-Neon laser and repeat the process using the violet laser pointer with the same grating and screen. Suppose that we observe that the second order maximum of the Helium-Neon laser’s diffraction pattern is located at the same spot on the screen as the third order maximum of the violet laser pointer’s diffraction pattern, which is 33.3 cm from the center of the central bright fringe (which is at the same location for both diffraction patterns).

(a) Determine the wavelength produced by the laser pointer.

(b) Determine the slit spacing for the diffraction grating.

(c) Calculate the number of slits per millimeter on the grating.

(d) How many maxima are there in the diffraction pattern of the Helium-Neon laser?

(e) How wide must the screen be so that all of the maxima are projected onto the screen?

Answer 1