Q: Which of the following is a correct application of Snell's law?

$n_1 \sin \theta_1 = n_2 \sin \theta_2$

Question 1

A beam of light passes from air (index of refraction $n_1 = 1.00$) into water ($n_2 = 1.33$) at an angle of incidence of $30^\circ$. What is the angle of refraction in the water?

Accepted Answer

$22.1^\circ$

Question 2

Which of the following best describes the principle of superposition for waves?

Accepted Answer

The net displacement at any point is the sum of the displacements due to each wave at that point.

Question 3

A thin film of oil ($n = 1.40$) floats on water ($n = 1.33$). For constructive interference in reflected light at normal incidence, what is the minimum nonzero thickness of the oil film for light of wavelength $560\ \mathrm{nm}$ in air?

Accepted Answer

$200\ \mathrm{nm}$

Question 4

A converging lens has a focal length of $10\ \mathrm{cm}$. An object is placed $30\ \mathrm{cm}$ from the lens. Where is the image formed?

Accepted Answer

$15\ \mathrm{cm}$ on the opposite side of the lens from the object

Question 5

Which of the following statements about real and virtual images is correct?

Accepted Answer

A real image can be projected onto a screen, while a virtual image cannot.

Question 6

A person is nearsighted (myopic) and can see objects clearly only up to $50\ \mathrm{cm}$ away. What type of lens and approximate focal length should be used in eyeglasses to correct their vision for distant objects?

Accepted Answer

A diverging lens with $f = -50\ \mathrm{cm}$

Question 7

A double-slit experiment uses slits separated by $0.20\ \mathrm{mm}$ and light of wavelength $600\ \mathrm{nm}$. What is the angular separation between the central maximum and the first-order maximum?

Accepted Answer

$0.172^\circ$

Question 8

Which of the following best describes the law of reflection?

Accepted Answer

The angle of incidence equals the angle of reflection, both measured from the normal.

Question 9

A ray of light in glass ($n = 1.50$) strikes the glass-air interface at an angle of $45^\circ$. What is the critical angle for total internal reflection at this interface?

Accepted Answer

$41.8^\circ$

Question 10

Which of the following is NOT a correct statement about the wave model of light?

Accepted Answer

Light waves require a medium to propagate.

Question 11

A diffraction grating has $5000$ lines per centimeter. What is the angular position of the first-order maximum for light of wavelength $500\ \mathrm{nm}$?

Accepted Answer

$14.5^\circ$

Question 12

A standing wave is formed on a string fixed at both ends. If the string is $1.2\ \mathrm{m}$ long and the speed of waves on the string is $60\ \mathrm{m/s}$, what is the frequency of the second harmonic?

Accepted Answer

$100\ \mathrm{Hz}$

Question 13

Which of the following is a correct application of Snell's law?

Accepted Answer

$n_1 \sin 	heta_1 = n_2 \sin 	heta_2$

Question 14

A person uses a magnifying glass (a converging lens) of focal length $5\ \mathrm{cm}$ to view an object placed $4\ \mathrm{cm}$ from the lens. What is the magnification?

Accepted Answer

$20$

Question 15

Which of the following best explains why a rainbow forms after a rain shower?

Accepted Answer

Dispersion of sunlight by water droplets causes different wavelengths to refract at different angles.

Question 16

In a double-slit experiment, what happens to the fringe spacing if the wavelength of the light is doubled?

Accepted Answer

The fringe spacing doubles.

Question 17

A ray of light passes from water ($n = 1.33$) into glass ($n = 1.50$) at an angle of $30^\circ$ to the normal. What is the angle of refraction in the glass?

Accepted Answer

$26.1^\circ$

Question 18

Which of the following statements about thin-film interference is correct?

Accepted Answer

A phase change of $\pi$ occurs upon reflection from a medium of higher refractive index.

Question 19

Which of the following is NOT a model used to describe the behavior of light?

Accepted Answer

The caloric model

Question 20

A convex mirror has a focal length of $-20\ \mathrm{cm}$. An object is placed $40\ \mathrm{cm}$ in front of the mirror. Where is the image formed?

Accepted Answer

$-13.3\ \mathrm{cm}$ (behind the mirror)

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