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Young’s Double Slit Contents: Interference Diffraction Young’s Double Slit Angle Distance Single slit Rayleigh Criterion. Interference. Sources. L 1. L 2. When the difference in distance ( L 1 - L 2 ) is an integer number of wavelengths (0, 1, 2, 3…) = Constructive
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Young’s Double Slit • Contents: • Interference • Diffraction • Young’s Double Slit • Angle • Distance • Single slit • Rayleigh Criterion
Interference Sources L1 L2 When the difference in distance (L1- L2) is an integer number of wavelengths (0, 1, 2, 3…) = Constructive remainder of a half (1/2, 1 1/2, 2 1/2, …) = Destructive TOC
Young’s Double Slit Experiment Monochromatic, coherent light Light spreads out from slits Screen has sum of two sources Interference pattern on screen Demo TOC
L2 – L1 = d sin Young’s Double Slit Experiment L1 Next Maxima d Central Maxima L2 d = slit separation TOC
L2 - L2 = d sin Young’s Double Slit Experiment L1 Next Maxima d Central Maxima L2 d = slit separation d sin = n (n = 0, 1, 2…) - constructive d sin = (n +1/2) - destructive TOC
Young’s Double Slit - Angle 1 | 2 | 3 | 4 TOC
Two slits are 3.00 x 10-6 m apart. What is the wavelength of the incident light if the bright fringes are separated by 6.00o? d sin = n d = 3.00 x 10-6 m, n = 1, = 6.00o W 314 nm
Two slits are 9.00 x 10-6 m apart. If 565 nm light is incident, what angle separates the central maxima, and the third fringe out? d sin = n d = 9.00 x 10-6 m, n = 3, = 565 x 10-9 m W 10.9o
s D Young’s Double Slit Experiment L1 Next Maxima d Central Maxima Similar triangles - set up proportion s = D d TOC
Young’s Double Slit Distance 1 | 2 | 3 | 4 TOC
520 nm light hits two slits separated by 2.5 x 10-5 m. What distance separates the bright fringes on the screen that is 5.0 m distant? s = D d d = 2.5 x 10-5 m, D = 5.0 m, = 520 x 10-9 m W .10 m
Light hits two slits separated by 2.50 x 10-5 m. If 5.70 cm separates the bright fringes on the screen that is 5.00 m distant, what is the wavelength of light being used? s = D d d = 2.50 x 10-5 m, D = 5.00 m, d = .0570 m W 285 nm
Central maximum of one is over minimum of the other • Rayleigh Criterion • = 1.22 • b • = Angle of resolution (Rad) • = Wavelength (m) • b = Diameter of circular opening (m) • (Telescope aperture) • the bigger the aperture, the smaller the angle you can resolve.
Rayleigh Criterion 1 | 2 TOC
What is the angular resolution of the 100 inch (2.54 m) diameter telescope on the top of Mt Wilson? (use 550 nm as the wavelength) (uh 550 nm = 550 x 10-9 m) = 1.22 b = ?, = 550 x 10-9 m, b = 2.54 m = 2.64173E-07 W 2.6 x 10-7 radians
What diameter telescope do you need to resolve two stars that are separated by 1.8 x 1011 m, but are 3.0 × 1017 m from us? (use 550 nm as the wavelength) (AU, 32 LY) hint = s/r = (1.8 x 1011 m)/(3.0 × 1017 m) = 1.22 b = 6.00 x 10-7, = 550 x 10-9 m, b = ? b = 1.12 m W 1.1 m