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Announcements Homework for tomorrow…
(Ch. 22, CQ2, Probs. 10, 12, & 13) 20.22: a) 6.7 x 1014 Hz b) 4.6 x 1014 Hz c) 1.4 20.24: a) 1.0 x 1010 Hz b) 1.6 x 10-4 s 20:26: a) 8.6 x 108 Hz b) 0.23 m Office hours… MW 12:30-1:30 pm TR am F 1-2 pm Tutorial Learning Center (TLC) hours: MW 8-10 am, 12-6 pm R 8-12 pm, 2-6 pm T 8-1 pm, 2-6 pm F 8-10 am, 2-5 pm
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Wave Optics (The Interference of Light & The Diffraction Grating)
Chapter 22 Wave Optics (The Interference of Light & The Diffraction Grating)
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Last time… Angular position of mth bright fringe…
Fringe spacing… Position of mth dark fringe…
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Quiz Question 1 Two rocks are simultaneously dropped into a pond, creating the ripples shown. The lines are the wave crests. As they overlap, the ripples interfere. At the point marked with a dot, The interference is constructive. The interference is destructive. The interference is somewhere between constructive and destructive. There’s not enough information to tell about the interference.
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i.e. 22.1 Double-slit interference of a laser beam
Light from a helium-neon laser (λ =633 nm) illuminates two slits spaced 0.40 mm apart. A viewing screen is 2.0 m behind the slits. What are the distances between the two m=2 bright fringes and between the m=2 dark fringes?
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Quiz Question 2 A laboratory experiment produces a double-slit interference pattern on a screen. The point on the screen marked with a dot is how much farther from the left slit than from the right slit? 1.0 . 1.5 . 2.0 . 2.5 . 3.0 .
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Quiz Question 3 A laboratory experiment produces a double-slit interference pattern on a screen. If the screen is moved farther away from the slits, the fringes will be closer together. in the same positions. farther apart. fuzzy and out of focus.
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Intensity of the Double-Slit Interference Pattern
If there were NO interference, the light intensity due to two slits would be twice the intensity of one slit (2I1). Instead, the superposition of the 2 waves creates bright and dark fringes. What is the intensity of the double-slit interference pattern at position y?
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Intensity of the Double-Slit Interference Pattern
If there were NO interference, the light intensity due to two slits would be twice the intensity of one slit (2I1). Instead, the superposition of the 2 waves creates bright and dark fringes. What is the intensity of the double-slit interference pattern at position y? Notice: Intensity oscillates between 0 and 4I1.
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Intensity of the Double-Slit Interference Pattern
The actual intensity from a double-slit experiment slowly decreases as |y| increases.
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Quiz Question 4 A laboratory experiment produces a double-slit interference pattern on a screen. If the amplitude of the light wave is doubled, the intensity of the central maximum will increase by a factor of √2. 2. 4. 8.
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22.3 The Diffraction Grating
The figure shows a diffraction grating in which N slits are equally spaced a distance d apart. Only 10 slits are shown here, but a practical grating will have hundreds or thousands of slits. What are the angular positions of the bright fringes in the interference pattern? Where does the mth bright fringe occur?
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22.3 The Diffraction Grating
The figure shows a diffraction grating in which N slits are equally spaced a distance d apart. Only 10 slits are shown here, but a practical grating will have hundreds or thousands of slits. What are the angular positions of the bright fringes in the interference pattern? Where does the mth bright fringe occur?
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