Lab 9 Pre-Lab

Please type your name in the form: Last, First

Please type the LAST 6 DIGITS of your student ID #:
(Note: No spaces, no dashes, no mistakes! If you type your ID wrong, I'm afraid you won't end up getting credit)

Due date: Mon Nov 14 before class.

Normally these questions will be submitted online AND you will print out a copy to turn in to your TA (If you fail to turn something in to your TA, you will get no PRELAB credit. Only copies of the online submissions will be accepted.)

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

Reflections: Lab 7 Electromagnetic Waves

1. I thought this lab was __________ USEFUL for learning about ray optics and lenses.

very
pretty
somewhat
barely
not at all

2. I thought this lab was __________ ENJOYABLE for a physics lab.

very
pretty
somewhat
barely
not at all

3. Consider the following diagram, in which a single lens is used to form an image of an arrow-shaped object. Which of the following statements is true?

If the object is moved to the right, the image will also move to the right.
If the object is moved to the right, the image will move to the left.
If the object is moved to the right, the image will not move since the focal length of the lens has not changed.
If the top half of the lens is blocked, only the bottom half of the image will form.
both (c) and (d) are true

Prelab 9 Questions:

1. Go to the PHET website (here) and open up the "Sound" simulation. Open up the third tab, which is "Two Source Interference". Drag the two speakers close together (so that the speaker cones partially overlap), and slow the speaker frequency down to around 200 Hz. Move the listener around and observe what happens. Can you find locations where the two waves destructively interfere? Can you find locations where the two waves constructively interfere? If you were in the laboratory, what would you observe in the presence of sound waves that were destructively interfering? How about constructively interfering? If you were in the laboratory, what would you observe at locations where light waves were destructively interfering? How about constructively interfering?

2. A He-Ne laser (λ = 633 nm) shines through a double slit of unknown separation d onto a screen 1.5 m away from the slit. The distance on the screen between the m=4 maxima on either side of the central maximum of the two-slit diffraction pattern is measured and is found to be 3.4 cm. What is the separation d of the two slits?

d =

3.A He-Ne laser (λ = 633 nm) shines through a single slit of unknown width D onto a screen 1.50 m away from the slit. The distance on the screen between the m=1 minima on either side of the central maximum of the diffraction pattern is measured and is found to be 2.3 cm. What is the width D of the slit?

D =

4.For the triangle shown at right, what is the angle θ in radians and in degrees? What would be your answer 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?

5. 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?


Thanks for your time and efforts!

Optional! - below is a space for any additional relevant comments, thoughts, or suggestions you have. If you want to elaborate on any "multiple choice" questions, do so here. It can also be about anything you'd like to tell or ask relating in some way to this class! If you expect a reply, however, it's much better to email Prof. Finkelstein.




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