Question 1

A light ray strikes a plane mirror at an angle of $$30^\circ$$ with respect to the normal. What is the angle between the incident ray and the reflected ray?

Accepted Answer

$$60^\circ$$

Question 2

A concave spherical mirror has a focal length of $$20\ \mathrm{cm}. An $$object is placed $$60\ \mathrm{cm} in $$front of the mirror. Using the mirror equation $$\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}$$, where $$f is $$the focal length, $$d_o is $$the object distance, and $$d_i is $$the image distance, what is the image distance $$d_i$$?

Accepted Answer

$$30\ \mathrm{cm}$$

Question 3

Which of the following best describes the difference in sign conventions for the focal length in the thin lens equation for convex and concave lenses?

Accepted Answer

Convex lenses have positive focal lengths, concave lenses have negative focal lengths.

Question 4

A ray of light passes from air ($$n=1.00) $$into glass ($$n=1.50) at an $$angle of $$45^\circ to $$the normal. Using Snell's Law $$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2$$, what is the angle of refraction $$\$$theta_2$$ inside the glass?

Accepted Answer

$$28.1^\circ$$

Question 5

In Young's double slit experiment, the distance between the slits is $$0.5\ \mathrm{mm}$$ and the screen is $$2\ \mathrm{m}$$ away. If the wavelength of light used is $$500\ \mathrm{nm}$$, what is the distance between adjacent bright fringes on the screen?

Accepted Answer

$$2.0\ \mathrm{mm}$$

Question 6

Which of the following statements about the dispersion of light through a prism is correct?

Accepted Answer

Shorter wavelengths are refracted more than longer wavelengths.

Question 7

According to Huygens' Principle, how does light propagate through a medium?

Accepted Answer

Every point on a wavefront acts as a source of secondary spherical wavelets.

Question 8

A single slit of width $$0.1\ \mathrm{mm} is $$illuminated with light of wavelength $$600\ \mathrm{nm}. At $$what angle $$	heta$$ does the first minimum occur in the diffraction pattern? (Use $$a \sin 	heta = m \lambda$$, $$m=1)$$

Accepted Answer

$$0.343\ \mathrm{rad}$$

Question 9

Which of the following is NOT a postulate of Einstein's Special Relativity?

Accepted Answer

Time and space are absolute and the same for all observers.

Question 10

A spaceship travels at $$0.8c$$ relative to Earth. According to an observer on Earth, a clock on the spaceship ticks slower by what factor? (Use the time dilation formula $$\Delta t = \gamma \Delta t_0$, $$\gamma = \frac{1}{\sqrt{1 - $$v^2/c^2$}}$)

Accepted Answer

$$1.67$$

Question 11

A rod is $$2.0\ \mathrm{m}$$ long in its own rest frame. What is its length as measured by an observer moving at $$0.6c$$ relative to the rod? (Use $$L = L_0$ \sqrt{1 - v^2$/c^2$$}$)

Accepted Answer

$$1.6\ \mathrm{m}$$

Question 12

Which equation correctly expresses the relationship between mass and energy in special relativity?

Accepted Answer

$$E = mc^2$

Question 13

Two cars move directly toward each other, each at $$0.7c$$ relative to the ground. What is the speed of one car as measured from the other using the relativistic velocity addition formula $$u' = \frac{u + v}{1 + \frac{uv}{c^2$}}$$?

Accepted Answer

$$0.94c$$

Question 14

A diffraction grating has $$5000$$ lines per centimeter. What is the angular position of the first-order maximum for light of wavelength $$600\ \mathrm{nm}$$? (Use $$d \sin 	heta = m \lambda)$$

Accepted Answer

$$1.72^\circ$$

Question 15

Which of the following best describes the effect of a polarizer on unpolarized light?

Accepted Answer

It transmits only the component of light oscillating in one direction.

Question 16

A real image is formed by a concave mirror when the object is placed:

Accepted Answer

Beyond the focal point but closer than the center of curvature.

Question 17

In a two-lens system, a diverging lens (focal length $$-10\ \mathrm{cm}) is $$placed $$20\ \mathrm{cm}$$ behind a converging lens (focal length $$+20\ \mathrm{cm}). An $$object is $$40\ \mathrm{cm} in $$front of the converging lens. What is the final image position relative to the diverging lens? (Assume thin lenses and use the lens equation sequentially.)

Accepted Answer

$$-20\ \mathrm{cm} (on $$the same side as the incoming light)

Question 18

Which of the following best explains why the sky appears blue during the day?

Accepted Answer

Shorter wavelengths of sunlight are scattered more than longer wavelengths by the atmosphere.

Question 19

If the path difference between two waves in Young's double slit experiment is $$\frac{3}{2}\lambda$$, what is observed at that point on the screen?

Accepted Answer

A dark fringe (destructive interference)

Question 20

A convex lens forms a virtual image when the object is placed:

Accepted Answer

Between the lens and its focal point.

Exam 3 Study Guide: Geometric Optics, Wave Nature of Light, and Special Relativity

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