Optics
Questions & Answers
Convex means the lens "bends in' at its center compared to the outer edges of the lens.
1. The wavelength of a monochromatic light changes from λo to λ = λo/n when it propagates from air into an optical medium such as glass. Does the frequency of the light change? Why?
4. In Measurement #3 how does the brightness of the reflected ray change when the incident angle changes from less than θ. to greater than θc? Why?
A ray of light is incident at the interface between medium A and medium B as shown in Figure 1a. The refractive index of medium A and medium B is 1.42 and 1.31 respectively. The light ray is totally internally reflected back into medium A. After that, medium B is replaced with a layer of water that has a refractive index of 1.33 as shown in Figure 1b. Determine if total internal reflection will also occur at the Medium A-water interface in Figure 1b. Assume that the incident angle in Figure 1a is the same as the incident angle in Figure 1b. Show your workings clearly and explain your reasoning.
. Explain what is meant by the coherence of a light wave. Under what conditions is light coherent over a given time interval? What about over a given distance? What is meant by coherence length?
6. What is meant by the radius of a spherical mirror? What does it mean when we say the radius is negative, rather than positive? How does one tell, given the radius, whether the mirror is concave or convex? Given the radius, how does one find the focal length of themirror?
11. What is meant by the interference of two light waves? Describe in detail what happens when a plane light wave passes through two slits spaced a small distance apart. What is Young's experiment? Describe in detail what happens when light reflects from thet op and bottom surfaces of a thin film. What is thin-film interference? Work through the different special cases of thin-film interference, regarding the possible combinations of refractive index on either side of the thin film. What are Newton's rings?
13. What is meant by diffraction? Compare and contrast diffraction and interference. What is meant by a diffraction pattern? Describe the diffraction pattern for light passing through a thin slit. What about through a double slit? Describe in detail, both qualitatively(with appropriate diagrams) and quantitatively (list relevant equations) the following:double-slit interference, single-slit diffraction, double-slit diffraction. Do the same for the diffraction pattern for light passing through a circular opening. What implications does this have for the resolution of an optical instrument? What is Rayleigh's criterion?
