Transcript of Lecture 25 Electromagnetic Waves-Ch 25 Wave Optics—Interference --Ch 17.
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- Lecture 25 Electromagnetic Waves-Ch 25 Wave OpticsInterference
--Ch 17
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- Slide 3
- Problems for Wednesday 25: 19, 22, 28, 29, 31 WB 25: 13-18
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- Electromagnetic Waves Slide 25-33
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- Sinusoidal Waves Single frequency (single color) and single
wavelength, . TRANSVERSE with B and E perpendicular to the
direction of motion. In vacuum velocity = c = 3.00 x 10 8 m/s Right
hand rule relates E, B and direction of propagation E = cB
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- Sinusoidal Waves Continued Wave traveling in the +x direction
with E polarized along the y-axis, and hence B along the
z-axis.
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- Sinusoidal Waves continued In vacuum, wave speed is c = 3.00x10
8 m/s = wavelength (spatial period) T = (temporal) period f =
c
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- Intensity Intensitypower incident on area A divided by A Point
Source
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- Polarization Linear or plane polarization: The electric field
oscillates along a straight line, the y-axis in our previous
example. A polarizer chooses a direction (called the polarizer
axis) along which the transmitted E-field oscillates. First
polarizers reduces intensity by
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- Photons Light particles: In some experiments, photo- electric
effect for example, light acts like a particle. Energy carried by
each photon
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- Checking Understanding A plane electromagnetic wave has
electric and magnetic fields at all points in the plane as noted
below. With the fields oriented as shown, the wave is moving A.into
the plane of the paper. B.out of the plane of the paper. C.to the
left. D.to the right. E.toward the top of the paper. F.toward the
bottom of the paper. Slide 25-34
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- Polarization Slide 25-37
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- Light passed through a polarizing filter has an intensity of
2.0 W/m 2. How should a second polarizing filter be arranged to
decrease the intensity to 1.0 W/m 2 ? Slide 25-38
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- The Electromagnetic Spectrum Slide 25-39
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- Problems 25: 19 E = 10 V/m in an electromagnetic wave. What is
B? 22: What is , f, and electric field amplitude? 28: I = 10 W/m 2
for a linearly polarized wave. Intensity through polarizer with b)
= 30 0 ?
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- More Problems 29: 25% passes polarizer. Angle of polarizer with
respect to electric field? 31: Unpolarized light with I = 350 W/m 2
What is I after two polarizers with second axis 35 0 to axis of
first?
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- Double-slit interference Diffraction gratings Thin-film
interference Single-slit diffraction Circular-aperture diffraction
Chapter 17 Wave Optics Topics: Sample question: The vivid colors of
this hummingbirds feathers have a sheen unlike that of ordinary
pigments, and they change subtly depending on the angle at which
theyre viewed. How does light interact with the feathers to produce
this bright display? Slide 17-1
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- Water Waves Spread Out behind a Small Opening Slide 17-6
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- Light Waves Also Spread Out Behind a Very Narrow Slit Slide
17-7
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- Youngs Double-Slit Interference Experiment Slide 17-8
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- Analyzing the Double-Slit Experiment Slide 17-9
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- Bright and Dark Fringes in the Double-Slit Experiment Slide
17-10
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- Problems 17 CQ1: frequency in water, glass CQ3: change in n,
does it change apparent color? MC17: what changes when light enters
glass? 1: travel time through piece of glass