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Question

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Conclusion Questions and Calculations:   You may check your approximate answers in the simulation

1. Why would a helicopter passing over or near a TV antenna cause a garbled or unusable TV signal?

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2. The simulation uses monochromatic light. If white light was used instead, what would be seen on the screen?

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3. As wavelength of the incident light increases (bluered) the maxima separation increases / decreases.

4. Two thin slits with separation of .0250mm are placed over monochromatic orange laser light at 610.nm. What is the small angle measurement from the central maximum (zero degrees, inline with the source) to the first maximum? __________________________

5. A beam of green light is split by thin double slit with separation of 0.0500mm and incident upon a screen some distance away. The angles of the first and second maximums are .584o and 1.17o respectively. What is the wavelength of the green light? __________________________

6. A single, monochromatic indigo light source is shined through an etched, flat prism with a slit separation of .0250mm. The resulting interference pattern is viewed on a screen 1.25m away. The third maximum is found to be 6.6cm from the central maximum. What is the wavelength of the indigo light? __________________________

7. Where are the first and second maxima? __________________________ and __________________________

8. When the two additive colors blue (475 nm) and green (510 nm) are incident in equal magnitudes upon a white screen, the subtractive color cyan results. Consider two beams, one blue and one green. The blue beam is shined through a double-slit diffraction grating with slit distance of 0.0400 mm and then displays an interference pattern on a screen 1.00m away. If the green beam is then shined from the same position as the blue beam, what size diffraction grating would be required for the green beam so only a cyan interference pattern would be seen on the screen? _____________

Explanation / Answer

(1)

Due to the Phenomenon of Interferce, the television reception is affected by the presence of other, unwanted signals. When the helicopters passes nearby TV's the the quality of signals are effected by the unwanted signal. The signal boosters faces more reception problems. Thus, the TV signals are unstable in this situation.

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(2)

If we use while light, instead monochromatic, the fringe pattern appered in colours. The visible wavelength pattern would form on the screen.

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(3)

The wavelength is proportional to the fringe width. As wavelength of incident light increases, the envolope of fringe pattern broaden and fringes move further apart. This implies the the maxima separtion would increases.

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( 4 )

Use the bright fringe condition

d sin = n

For first order ( smallest angle ), n =1

sin = / d = 610.nm / .0250mm = 610e-9 / 0.025e -3 = 0.0244

Thus, the angle

= sin -1 (  0.0244 )

= 1.398 degree

= 1.4 degree ( approximately )

( Please post other questions separately )

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