On a sunny summer day, with the sun overhead, you can stand under a tree and look on the ground at the pattern of light that has passed through gaps between the leaves. You may see illuminated circles of varying brightness. Why are there circles, when the gaps between the leaves have irregular shapes?

A ray of white light strikes the surface of a $4.0$-cm-thick slab of flint glass as shown in Figure P19.47. As the ray enters the glass, it is dispersed into its constituent colors. Estimate how far apart the rays of deepest as we discussed earlier red and deepest violet light are as they exit the bottom surface. Which exiting ray is closer to point $\mathrm{P}$ ?

The index of refraction in flint glass is 1.66 for blue light and 1.61 for red light, with the values for other colors between these limits. A ray of white light traveling from left to right through a slab of flint glass undergoes dispersion as it exits the slab and enters the air. If the exiting ray strikes the right surface of the slab at an angle of $30.0 ^ { \circ }$ from the normal to the surface, what is the angle of refraction (a) for the blue light and (b) for the red light? (c) A flat opaque screen is placed in the path of the refracted rays such that the red ray strikes perpendicular to the screen. If the distance along the refracted red ray from slab to screen is 0.50 m, what is the distance between the point of red light and the point of blue light in the rainbow produced on the screen? (Use the small-angle approximation.)

A light ray travels inside a horizontal plate of glass, striking its upper surface at an angle of incidence of $60 ^ { \circ }$. This ray is totally internally reflected at the glass-air boundary. A liquid is then poured on top of the glass. What is the largest index of refraction that the liquid could have such that the ray is still totally internally reflected?

The writing on the passenger-side mirror of your car says "Warning! Objects in mirror are closer than they appear." There is no such warning on the driver's mirror. Consider a typical convex passenger-side mirror with a focal length of -80 cm. A 1.5-m-tall cyclist on a bicycle is 25 m from the mirror. You are 1.0 m from the mirror, and suppose, for simplicity, that the mirror, you, and the cyclist all lie along a line. a. How far are you from the image of the cyclist? b. How far would you have been from the image if the mirror were flat? c. What is the image height? d. What would the image height have been if the mirror were flat? e. Why is there a label on the passenger-side mirror?

Mourning doves have a small BlD patch of iridescent feathers. The color is produced by a $330-\mathrm{nm}-$ thick layer of keratin $(n=1.56)$ with air on both sides that is found around the edge of the feather barbules. For what wavelength or wavelengths would this structure produce constructive interference?

Two narrow slits are illuminated by light of wavelength $\lambda$. The slits are spaced 20 wavelengths apart. What is the angle, in radians, between the central maximum and the m = 1 bright fringe?

A photographer focuses his camera on his subject. The subject then moves closer to the camera. To refocus, should the lens be moved closer to or farther from the detector? Explain.

Suppose you have two pinhole cameras. The first has a small round hole in the front. The second is identical except it has a square hole of the same area as the round hole in the first camera. Would the pictures taken by these two cameras, under the same conditions, be different in any obvious way? Explain.

Suppose you have two pinhole cameras. The first has a small round hole in the front of the camera. The second is identical in every regard, except that it has a square hole of the same area as the round hole in the first camera. Would the pictures taken by these two cameras, under the same conditions, be different in any obvious way? Explain.

A 1.0-cm-tall object is 10 cm in front of a converging lens that has a 30 cm focal length. a. Use ray tracing to find the position and height of the image. To do this accurately, use a ruler or paper with a grid. Determine the image distance and image height by making measurements on your diagram. b. Calculate the image position and height. Compare with your ray-tracing answers in part a.

A laser beam in air is incident on a liquid at an angle of $37 ^ { \circ }$ with respect to the normal. The laser beam's angle in the liquid is $26 ^ { \circ }$. What is the liquid's index of refraction?

A swatch of pure red fabric is viewed through a green filter. The fabric appears
A. Red.
B. Green.
C. Yellow.
D. Black.

Quality control systems have been developed to remotely measure the diameter of wires using diffraction. A wire with a stated diameter of $170 \mu \mathrm{m}$ blocks the beam of a $633 \mathrm{~nm}$ laser, producing a diffraction pattern on a screen $50.0 \mathrm{~cm}$ distant. The width of the central maximum is measured to be $3.77 \mathrm{~mm}$. The wire should have a diameter within $1 \%$ of the stated value. Does this wire pass the test?