PHYS 2020: Prelab 11

Physics 2020 Students

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PRELAB QUESTIONS: (to be turned in upon arriving at lab)

1. Read Giancoli sections 24.3 thoroughly.

2. Read the lab instructions thoroughly.

3. For the triangle shown at right, what is the angle θ in radians and in degrees? What would be your answers if you made the small angle approximation (sin θ ≈ tan θ ≈ θ)? What would be your % error in θ if you made the small angle approximation?

4. Why is it ok to stare at a 100 watt light bulb, considering that a 0.001 watt laser aimed into your eye will damage it? (Try to answer beyond just "it's brighter" or "it's more damaging", we are curious how you would explain why? After all, the laser power is 100,000 times SMALLER, how might a physicist explain this apparently curious fact that the laser is nevertheless much more damaging? )

5. For this one, we just want your ideas. Full credit for effort, you aren't expected to necessarily know the answers yet! We just want to know your initial good ideas. (AFTER taking the lab, you should be able to answer these questions!)

Light from a laser passes through two very narrow slits and onto a screen, as shown in the diagram below. The top picture of light and dark areas shows what appears on the screen when the laser is first turned on. A single change is made to the apparatus, resulting in the new pattern on the screen, shown in the bottom picture. (Below the figure we have some questions)

For each of the following quantities, determine whether a change to that quantity could produce the new pattern shown. If so, select whether the quantity should be increased or decreased to result in the new pattern. (Remember, we aren't grading these questions for correctness, just for effort.)
 
No effect on the pattern
Should be increased
Should be decreased
Not Answered
The distance between the slits
The wavelength of the laser light
The distance from the slits to the screen

In the space below, briefly explain the reasoning you used for your answers above.


Thanks for your time and efforts!

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