A red laser from the physics lab is marked as producing 632.8-nm light. When lig

Question

A red laser from the physics lab is marked as producing 632.8-nm light. When light from this laser falls on two closely spaced slits, an interference pattern formed on a wall several meters away has bright red fringes spaced 4.50mm apart near the center of the pattern. When the laser is replaced by a small laser pointer, the fringes are 4.64mm apart.

Part A

What is the wavelength of light produced by the pointer?

Express your answer to three significant figures and include the appropriate units nm

A red laser from the physics lab is marked as producing 632.8-nm light. When light from this laser falls on two closely spaced slits, an interference pattern formed on a wall several meters away has bright red fringes spaced 4.50mm apart near the center of the pattern. When the laser is replaced by a small laser pointer, the fringes are 4.64mm apart.

Part A

What is the wavelength of light produced by the pointer?

Express your answer to three significant figures and include the appropriate units nm

Explanation / Answer

The fringe width in the double slit interference pattern is given by

fringe width = D? / d

Where D = distance of the screen from the slits
d = separation between the slits

The wave length ? is directly proportional to the fringe width.

?1 / ?2 = 5 / 5.13
?2 = ?1 x 5.13 / 5 = 632.8 x 5.13 / 5 = 649.2528 nm is the wave length of light produced by the pointer.

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