A metallic sheet has a large number of parallel slits,5.0 mm wide and 20 cm apart.This sheet is used as a diffraction grating for microwaves.A wide parallel beam of microwaves is incident normally on the sheet.If the microwave wavelength is 6.0 cm,what is the largest angle from the normal,at which an intensity maximum occurs?
A)64°
B)69°
C)74°
D)79°
E)84°

Question

Quizplus · Accepted Answer

The largest angle from the normal at which an intensity maximum occurs is given by the equation:sin θ = mλ/dwhere m is the order of the maximum, λ is the wavelength of the microwaves, and d is the distance between the slits. In this case, m = 1 (the first order maximum), λ = 6.0 cm, and d = 20 cm. Substituting these values into the equation, we get:sin θ = (1)(6.0 cm)/(20 cm) = 0.3Taking the inverse sine of both sides, we get:θ = 17.5°Since the intensity maximum occurs on both sides of the normal, the largest angle from the normal at which an intensity maximum occurs is 2θ = 35°.

A Metallic Sheet Has a Large Number of Parallel Slits,5