Q: Light travels through 2 meters of water (index of refraction $$n = 1.33). $$What is the time taken for light to travel this distance? ($$c = 3.0 \\times 10^8$ m/s)

$$t = \\dfrac{2}{c/n} = \\dfrac{2 \\times 1.33}{3.0 \\times 10^8$}$$

Q: A ray of light passes from air ($$n_1 = 1.00$) into glass (n_2$ = 1.46) at an $$incident angle of $$30^\\circ. $$What is the angle of refraction in the glass?

$$\\$$theta_2$$ = \\arcsin \\left( \\dfrac{n_1$}{n_2$} \\sin \\$$theta_1$$ \\right )$$

Q: A laser beam travels through air and glass for 2 nanoseconds. How much farther does the beam travel in air than in glass? ($$n_{air} = 1.00$$, $$n_{glass} = 1.46$$, $$c = 3.0 \\times 10^8$ m/s)

Distance difference $$= c \\times t \\left( 1 - \\dfrac{1}{1.46} \\right )$$

Q: Which law describes the relationship between the angles of incidence and refraction when light passes between two media?

Snell's Law: $$n_1$$ \\sin \\$$theta_1$$ = $$n_2$$ \\sin \\$$theta_2$$

Q: A ray of light is incident on a block of glass ($$n = 1.46) at$$ $$70^\\circ$$ and travels through a block of length $$7.5 cm. $$What is the vertical distance $$y$$ below the top of the block where the ray exits?

$$y = 7.5 \\tan( $$heta_2$$)$$, where $$\\$$theta_2$$ is found using n_1$ \\sin \\$$theta_1$$ = n_2$ \\sin \\$$theta_2$$

Q: What is the critical angle $$\\theta_{c}$$ for total internal reflection for light traveling from glass ($$n = 1.46) $$into air ($$n = 1.00$$)?

$$\\theta_{c} = \\arcsin \\left( \\dfrac{n_{air}}{n_{glass}} \\right )$$

Q: A light ray in air ($$n = 1.00) $$strikes water ($$n = 1.33) at$$ $$60^\\circ to $$the normal. What is the angle $$\\theta$$ between the reflected and refracted rays?

$$\\theta = 60^\\circ + \\$$theta_2$$, where $$\\$$theta_2 is $$found using Snell's Law

Question 1

According to Huygen's Principle, what happens at every point on a wave front?

Accepted Answer

Each point acts as a source of spherical wavelets, and the new wave front is formed by the tangent to these wavelets.

Question 2

A laser beam strikes a flat mirror at an angle of incidence of $$30^\circ. $$What is the angle of reflection?

Accepted Answer

$$30^\circ$$

Question 3

Which equation correctly relates the index of refraction $$n to $$the speed of light $$v in a $$material?

Accepted Answer

$$n = \dfrac{c}{v}$$

Question 4

Light travels through 2 meters of water (index of refraction $$n = 1.33). $$What is the time taken for light to travel this distance? ($$c = 3.0 \times 10^8$ m/s)

Accepted Answer

$$t = \dfrac{2}{c/n} = \dfrac{2 \times 1.33}{3.0 \times 10^8$}$$

Question 5

A ray of light passes from air ($$n_1 = 1.00$) into glass (n_2$ = 1.46) at an $$incident angle of $$30^\circ. $$What is the angle of refraction in the glass?

Accepted Answer

$$\$$theta_2$$ = \arcsin \left( \dfrac{n_1$}{n_2$} \sin \$$theta_1$$ \right )$$

Question 6

If a light ray enters water ($$n = 1.33) $$from air ($$n = 1.00) at$$ $$45^\circ to $$the normal, does the ray bend toward or away from the normal?

Accepted Answer

Toward the normal

Question 7

A laser beam travels through air and glass for 2 nanoseconds. How much farther does the beam travel in air than in glass? ($$n_{air} = 1.00$$, $$n_{glass} = 1.46$$, $$c = 3.0 \times 10^8$ m/s)

Accepted Answer

Distance difference $$= c \times t \left( 1 - \dfrac{1}{1.46} \right )$$

Question 8

Which law describes the relationship between the angles of incidence and refraction when light passes between two media?

Accepted Answer

Snell's Law: $$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2$$

Question 9

A ray of light is incident on a block of glass ($$n = 1.46) at$$ $$70^\circ$$ and travels through a block of length $$7.5 cm. $$What is the vertical distance $$y$$ below the top of the block where the ray exits?

Accepted Answer

$$y = 7.5 \tan(	$$heta_2$$)$$, where $$\$$theta_2$$ is found using n_1$ \sin \$$theta_1$$ = n_2$ \sin \$$theta_2$$

Question 10

What is the critical angle $$\theta_{c}$$ for total internal reflection for light traveling from glass ($$n = 1.46) $$into air ($$n = 1.00$$)?

Accepted Answer

$$\theta_{c} = \arcsin \left( \dfrac{n_{air}}{n_{glass}} \right )$$

Question 11

When light passes from a material with a higher index of refraction to a lower index, what happens to the direction of the refracted ray?

Accepted Answer

It bends away from the normal

Question 12

Which of the following best describes specular reflection?

Accepted Answer

Reflection from a smooth surface where rays remain parallel after reflection

Question 13

A light ray in air ($$n = 1.00) $$strikes water ($$n = 1.33) at$$ $$60^\circ to $$the normal. What is the angle $$\theta$$ between the reflected and refracted rays?

Accepted Answer

$$\theta = 60^\circ + \$$theta_2$$, where $$\$$theta_2 is $$found using Snell's Law

Question 14

Which statement is true about the speed of light in different materials?

Accepted Answer

Light travels fastest in vacuum.

Question 15

If the index of refraction of ice is $$1.31$$, what is the speed of light in ice?

Accepted Answer

$$v = \dfrac{c}{1.31}$$

Question 16

Which of the following is NOT a consequence of Huygen's Principle?

Accepted Answer

Wave fronts always travel in straight lines regardless of the medium.

Question 17

A ray of light passes from diamond ($$n = 2.42) $$into air ($$n = 1.00). $$What is the minimum angle of incidence for total internal reflection?

Accepted Answer

$$\theta_c = \arcsin \left( \dfrac{1.00}{2.42} \right )$$

Question 18

Which scenario will result in diffuse reflection?

Accepted Answer

Light reflecting off a rough wall

Reflection, Refraction, and Wave Properties of Light: Study Notes for College Physics

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