Physics Lab

Physics 132 - Spring 2016

Experiment: Wave Optics

Lab Report Questions

(12 points)

1. Define wavelength and frequency in your own words and state the relation between them,

(equation statement). (0.5 point)

2. Describe the pattern observed from diffraction around a straight edge. Based on your

observation with the straight edge experiment, do you conclude light is a wave or a particle?

Why?

3. When you illuminate the opaque disk in the straight edge/opaque disk using the laser through

the lens, was there a light or dark spot at the center of the screen? Why?(1.0 point)

4. Is there a specific reason for using lasers in this experiment, and not ordinary white light, if yes

what is it? (there may be more than one reason) (1.5 points)

5. For single slit diffraction how would the width of the central maxima or the central bright band

change

a) If the wavelength is increased (1.0 point)

b) If the slit width “a” is decreased (1.0 point)

6. Pretend you redid the diffraction grating section and arrived at this data: L = 1m, d = 3.33 x 104

cm, y (distance from center to first bright spot) = 22.1cm, λ=656nm (red light).

Now pretend you leave the equipment setup the same but pass blue light (λ=452nm) through the

diffraction grating. What y distance will the blue light be diffracted to? Is this closer to or

farther away from the center? (2.5 point)

7. A light spectrum is formed on the screen using a diffraction grating. The entire apparatus made

up of laser, grating and the screen is now immersed in a liquid with refractive index 1.5. Do the

bright spots on the screen get closer together, farther apart, remain the same or disappear

entirely? Explain (1.5 points)

8. Light with wavelength of λ = 500 nm is incident on a diffraction grating. The screen is placed

at a distance L = 2m from the diffraction grating. The grating has N = 500/mm parallel slits

(used to calculate d). Find the distance y between the 2nd bright spots or the second order

maxima on...