Question 1

A swimmer looks straight up from underwater at the overhead lights located 10 m above the water’s surface. How far above the surface do the lights appear to be to the swimmer? The index of refraction of the water is $n = 1.33$.

Accepted Answer

$13.3\ \mathrm{m}$

Question 2

A beam of light passes from one material into another. If the speed of light in medium A is $v_A$ and in medium B is $v_B$, what is the ratio $v_A/v_B$ if the indices of refraction are $n_A = 1.5$ and $n_B = 2.0$?

Accepted Answer

$1.33$

Question 3

An object is placed at $15\ \mathrm{cm}$ in front of a concave spherical mirror. An image of the object appears $5\ \mathrm{cm}$ in front of the mirror. What is the mirror’s focal length?

Accepted Answer

$7.5\ \mathrm{cm}$

Question 4

An object is placed $60\ \mathrm{cm}$ in front of a concave spherical mirror with radius $60\ \mathrm{cm}$. What is the location of the image relative to the mirror?

Accepted Answer

$60\ \mathrm{cm}$ behind

Question 5

Which of the following statements is correct regarding light passing from air into glass?

Accepted Answer

When light goes from air into glass, its velocity decreases

Question 6

A positive magnification indicates that an image is:

Accepted Answer

Upright

Question 7

Coherent monochromatic light ($\lambda = 458\ \mathrm{nm}$) passes through two narrow parallel slits to illuminate a screen $1\ \mathrm{m}$ away. If the distance between the central fringes is $d = 8.8\ \mathrm{mm}$, what is the distance between the two slits?

Accepted Answer

$8.8\ \mu\mathrm{m}$

Question 8

An engineer wants to expand the reach of their radio transmission, broadcasting at $899.38\ \mathrm{kHz}$, by building a second transmitting antenna $1\ \mathrm{km}$ away from the existing transmitter. What can be said about the frequencies at the same time as the original antenna, taking care that all receivers in the area listen to the signal?

Accepted Answer

It depends where the listener is located

Question 9

A monochromatic plane wave ($\lambda = 128\ \mathrm{nm}$) is normally incident on a diffraction grating with $750\ \mathrm{slits/mm}$. What is the angle of the interference maximum for $n = 3$?

Accepted Answer

$34^\circ$

Question 10

An observer sets out to count the craters on the moon by eye. Assuming the observer’s eye has a diameter of $6\ \mathrm{mm}$, and the moon is $3.8 	imes 10^5\ \mathrm{km}$ away, approximately what is the smallest distance between craters such that they can be individually resolved? (Assume $\lambda = 550\ \mathrm{nm}$)

Accepted Answer

$100\ \mathrm{km}$

Question 11

Unpolarized light is passed through two successive polaroid filters. The second has its transmission axis at $45^\circ$ relative to the first. What percentage of the light gets through?

Accepted Answer

$25\%$

Question 12

A plane mirror is placed in a fish tank full of water ($n = 1.33$). A fish swims toward its image in the mirror at a speed of $10\ \mathrm{cm/s}$. At what speed are the fish and its image converging?

Accepted Answer

$20\ \mathrm{cm/s}$

Question 13

A diamond ring is observed under white light. Which property of diamond is primarily responsible for its 'fire' (the colorful sparkle)?

Accepted Answer

High index of refraction causing strong dispersion

Question 14

A patient receives polarized sunglasses to reduce glare while driving. What is the main physical principle that allows these glasses to work?

Accepted Answer

Polarization by reflection from horizontal surfaces

Question 15

A microscope uses a $40	imes$ objective lens with a numerical aperture of $0.65$. What is the smallest resolvable detail using green light ($\lambda = 550\ \mathrm{nm}$)?

Accepted Answer

$0.52\ \mu\mathrm{m}$

Question 16

A laser beam passes from air ($n = 1.00$) into water ($n = 1.33$) at an angle of $45^\circ$ to the normal. What is the angle of refraction in the water?

Accepted Answer

$32^\circ$

Question 17

A camera lens with a focal length of $50\ \mathrm{mm}$ is used to photograph a person standing $2\ \mathrm{m}$ away. Where is the image formed?

Accepted Answer

$52.6\ \mathrm{mm}$ behind the lens

Question 18

A fiber optic cable uses total internal reflection to transmit signals. What is the minimum angle of incidence for total internal reflection if the core has $n = 1.50$ and the cladding has $n = 1.45$?

Accepted Answer

$75.5^\circ$

Optics and Wave Phenomena: Analytical Physics IIb Exam Practice Study Guide

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