Lesson: Single-Slit Diffraction Physics • 9th Grade

In this lesson, we will learn how to calculate the positions of points of maximum and minimum intensity in diffraction patterns generated by single-slits

Lesson Plan

Students will be able to

use the small-angle approximation to relate the angular distance, , from the center of an aperture of width , of a diffraction maximum of order that is produced when light waves of wavelength pass through the aperture, applying the equation ,
relate the distance, , of the central maximum of a single-slit diffraction pattern produced by light waves of wavelength passing through an aperture of width , from the center of an interference maximum of order , where the interference pattern is generated on a screen at a distance from the aperture, using the equation .

Lesson Worksheet

Q1:

Light of wavelength 550 nm passes through a slit 7.55 μm in width and falls onto a screen 12.5 cm in front of the slit, producing a diffraction pattern that has its central maximum at a point directly in front of the slit. The angle that light in the diffraction pattern makes with the line passing through the center of the slit and the center of the diffraction pattern is small enough for . What is the distance from the central maximum of the diffraction pattern to the first minimum of the pattern?

Q2:

Light of wavelength 475 nm passes through a slit 8.25 μm in width and falls onto a screen 4.6 cm in front of the slit, producing a diffraction pattern that has its central maximum at a point directly in front of the slit. The angle that light in the diffraction pattern makes with the line passing through the center of the slit and the center of the diffraction pattern is small enough for . What is the width of the central maximum of the pattern? Answer to two significant figures.

Q3:

Light of wavelength passing through a narrow slit of width falls on a screen where a diffraction pattern is produced. Which of the following formulas correctly relates and to the angle from a line that intersects the center of the slit and the center of the diffraction pattern to a line that intersects the center of the slit and a minimum of the diffraction pattern of order ?