1.
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A line of 11 radio transmitters is built so that each transmitter produces a signal with exactly the same amplitude and phase. Wave crests appear as light gray and wave troughs appear dark in the simulation (the position is given in centimeters). What type of wave front does Huygens' principle predict in front of these transmitters if their separation is small compared to the signal's wavelength? Start Note: wait for the frame counter in the upper left-hand corner of the simulation. Interactive Hint Build up the transmitter array from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 sources.
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| A plane wave front traveling along a line perpendicular the transmitters.
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| A plane wave front traveling along a line connecting the ends of the transmitters.
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| A circular wave front centered on the middle transmitter.
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2.
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Two point sources act very much like a double slit as shown in the above animation. Wave crests appear as light gray and wave troughs appear darker (the position is given in centimeters). The source separation does not change. How will the interference pattern change if the frequency of both sources is doubled? Start Note: wait for the frame counter in the upper left-hand corner of the simulation. Interactive Hint Halve the frequency and observe the result.
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| The separation between wave crest and trough will be halved and the angle between the fringes will double.
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| The separation between wave crest and trough will double and the angle between the fringes will be halved.
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| The separation between wave crest and trough will be halved and the angle between the fringes will be halved.
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| The interference pattern will change very little.
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3.
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An electromagnetic wave (infrared light) is shown (the dark red central wave) traveling to the right through two media (I and II) of different indices of refraction n1 and n2, respectively (position is given in microns, mm). As the light encounters a change in index of refraction, part of it is transmitted through and part is reflected backwards. Hence, in region I the wave central wave is a mixture of a right-moving and left-moving wave as shown by the right-moving (the blue lower wave) and left-moving (the red upper wave) components. Look at the following 5 animations and decide which of the following statements is false. | A. As n2 gets larger, the fraction of the initial wave that gets transmitted decreases. | | B. The sum of the amplitudes for the transmitted and reflected waves equals the initial amplitude. | | C. The reflected wave has a 180o phase shift compared to the initial wave. | | D. The sum of the initial and reflected waves in region 1 look more and more like a standing wave as n increases. | | E. If n2=1, there would be no reflected wave. |
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| Statement A.
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| Statement B.
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| Statement C.
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| Statement D.
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| Statement E.
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| None of the Statements.
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4.
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An electromagnetic wave (infrared light) is shown (the dark red central wave) traveling to the right through two media (I and II) of different indices of refraction n1 and n2, respectively (position is given in microns, mm). As the light encounters a change in index of refraction, part of it is transmitted through and part is reflected backwards. Hence, in region I the wave central wave is a mixture of a right-moving and left-moving wave as shown by the right-moving (the blue lower wave) and left-moving (the red upper wave) components. Look at the following 5 animations and decide which of the following statements is false. | A. As n2 gets smaller, the fraction of the initial wave that gets reflected increases. | | B. The sum of the amplitudes for the transmitted and reflected waves does not equal the initial amplitude. | | C. The reflected wave has a no phase shift compared to the initial wave. | | D. If n2=2.5, there would be no reflected wave. |
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| Statement A.
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| Statement B.
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| Statement C.
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| Statement D.
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| None of the Statements.
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5.
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An electromagnetic wave (infrared light) is shown traveling to the right through three media (I, II, and III) of different indices of refraction (position is given in microns, mm). You can change the thickness of the material in region II by click dragging the second surface or by using the text field below. As the light encounters a change in index of refraction, part of it is transmitted through and part is reflected backwards. Hence, in regions I and II the wave shown is a mixture of a right-moving and left-moving wave. In order to get no reflected wave in region I, where must you place the interface between regions II and III so that this interface is the closest to the region I/II interface? Start Set the thickness of the middle medium to: Note: keep d > 1 and < 28
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| x=21.6 mm.
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| x=23.3 mm.
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| x=25.0 mm.
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| x=26.6 mm.
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6.
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An electromagnetic wave (infrared light) is shown traveling to the right through three media (I, II, and III) of different indices of refraction (position is given in microns, mm). You can change the thickness of the material in region II by click dragging the second surface or by using the text field below. As the light encounters a change in index of refraction, part of it is transmitted through and part is reflected backwards. Hence, in regions I and II the wave shown is a mixture of a right-moving and left-moving wave. In order to get no reflected wave in region I, where must you place the interface between region II and III? Start Set the thickness of the middle medium to: Note: keep d > 1 and < 28
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| x=22.5 mm.
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| x=25.0 mm.
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| x=27.5 mm.
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| x=30.0 mm.
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7.
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An electromagnetic wave (infrared light) is shown traveling to the right through three media (I, II, and III) of different indices of refraction (position is given in microns, mm). You can change the thickness of the material in region II by click dragging the second surface or by using the text field below. As the light encounters a change in index of refraction, part of it is transmitted through and part is reflected backwards. Hence, in regions I and II the wave shown is a mixture of a right-moving and left-moving wave. In order to get no reflected wave in region I, where must you place the interface between region II and III? Start Note: the index of fraction in region II is n2=(n3)1/2 so the amplitude of the reflected wave can be zero if the thickness is chosen correctly. Set the thickness of the middle medium to: Note: keep d > 1 and < 28
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| x=22.5 mm.
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| x=25.0 mm.
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| x=27.5 mm.
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| x=30.0 mm.
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8.
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An electromagnetic wave is shown traveling to the right through three media (I, II, and III) of different indices of refraction (position is given in millimeters). You can change the index of refraction in region II. As the wave encounters a change in index of refraction, part of it is transmitted through and part is reflected backwards. Hence, in regions I and II the wave shown is a mixture of a right-moving and left-moving wave. In order to get no reflected wave in region I, what index of refraction, 1<n<2.5, must region II have? Start Set the index of refraction in the middle medium to: Note: keep ratio above 1 and less than 2.5
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| n=1.25.
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| n=1.33.
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| n=1.5.
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| n=1.66.
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| n=2.0.
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9.
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An electromagnetic wave is shown traveling to the right through three media (I, II, and III) of different indices of refraction (position is given in millimeters). You can change the index of refraction in region II. As the light encounters a change in index of refraction, part of it is transmitted through and part is reflected backwards. Hence, in regions I and II the wave shown is a mixture of a right-moving and left-moving wave. In order to get no reflected wave in region I, what index of refraction, 1<n<2.5, must region II have? Start Set the index of refraction in the middle medium to: Note: keep ratio above 1 and less than 2.5
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| n=1.25.
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| n=1.33.
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| n=1.5.
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| n=1.66.
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| n=2.0.
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10.
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How will the double slit interference pattern shown in the above animation change if the frequency of both sources is doubled and their separation is halved (the position is given in centimeters)? Start Note: wait for the frame counter in the upper left-hand corner of the simulation. Interactive Hint Halve the separation but keep the frequency constant and observe the result.
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| The separation between wave crest and trough will be halved and the angle between the fringes will double.
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| The separation between wave crest and trough will double and the angle between the fringes will be halved.
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| The separation between wave crest and trough will be halved and the angle between the fringes will not change.
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| The interference pattern will change very little.
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11.
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The red circle can be click-dragged by pressing the edit button after you start (the position is given in millimeters ). Where should the source on the right be placed in order that the first order constructive interference fringe propagates at an angle of 37 degrees with respect to the x axis? Start Note: wait for the frame counter in the upper left-hand corner of the simulation.
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| -.25 mm.
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| 0.25 mm.
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| 0.50 mm.
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| 0.75 mm.
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12.
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A double slit is hidden somewhere below the animation. You can measure (x,y) coordinates by click-dragging inside the animation (the position is given in nanometers). What is the slit separation? Start Note: wait for the frame counter in the upper left-hand corner of the simulation.
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| 1 nm. |
| 2 nm.
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| 3 nm.
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| 4 nm.
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