Lesson: Two-Slit Interference

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

Worksheet: 12 Questions

Q1:

Light passes through a sheet in which there are two parallel narrow slits 12.8 μm apart. The light from the slits is incident on a screen parallel to the sheet, where a pattern of light and dark fringes is observed. A line 𝐿 runs perpendicular to the surface of the sheet and the direction of the slits. The line 𝐿 intersects the central bright fringe of the pattern on the screen. The angle between 𝐿 and a line that intersects the center of the bright fringe closest to the central bright fringe is 3.09. What is the wavelength of the light? Give your answer to three significant figures.

Q2:

Light with a wavelength of 636 nm passes through a sheet in which there are two parallel narrow slits. The light from the slits is incident on a screen parallel to the sheets, 1.08 m away, where a pattern of light and dark fringes is observed. A line 𝐿 runs perpendicular to the surface of the sheet and the direction of the slits. The line 𝐿 intersects the central bright fringe of the pattern on the screen. The distance on the screen from 𝐿 to the center of the bright fringe nearest to the central bright fringe is 6.11 cm. What is the distance between the slits?

Q3:

Light with a wavelength of 625 nm passes through a sheet in which there are two parallel narrow slits. The light from the slits is incident on a screen parallel to the sheet, where a pattern of light and dark fringes is observed. A line 𝐿 runs perpendicular to the surface of the sheet and the direction of the slits. The line 𝐿 intersects the central bright fringe of the pattern on the screen. The angle between 𝐿 and a line that intersects the center of the bright fringe closest to the central bright fringe is 2.67. What distance separates the slits on the sheet? Give your answer to three significant figures.

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