Q: A fiber optic cable has a core with $$n_{core} = 1.50$$ and cladding with $$n_{clad} = 1.40. $$What is the critical angle for total internal reflection at the core-cladding interface?

$$\theta_c = \arcsin\left(\frac{1.40}{1.50}\right) = 69.1^\circ$$

Question 1

Which of the following statements about the image formed by a plane mirror is correct?

Accepted Answer

The image is upright, the same size as the object, and as far behind the mirror as the object is in front.

Question 2

A car’s rearview mirror is a plane mirror. If a driver is 2 meters in front of the mirror, how far behind the mirror does the image of the driver appear?

Accepted Answer

$$2\ \mathrm{m} ($$the same distance as the object is in front)

Question 3

Which property of a plane mirror image explains why emergency vehicles have their lettering reversed?

Accepted Answer

The image is reversed left to right.

Question 4

A concave spherical mirror has a radius of curvature $$R = 20\ \mathrm{cm}. $$What is its focal length $$f$$?

Accepted Answer

$$f = 10\ \mathrm{cm}$$

Question 5

Which of the following best describes the image formed by a convex mirror?

Accepted Answer

Virtual, upright, and reduced in size

Question 6

A $$3.0\ \mathrm{cm}$$ tall object is placed $$15\ \mathrm{cm} in $$front of a concave mirror with a focal length of $$5.0\ \mathrm{cm}. $$Where is the image located?

Accepted Answer

$$d_i = 7.5\ \mathrm{cm} ($$real)

Question 7

Which equation correctly relates the object distance $$d_o$$, image distance $$d_i$$, and focal length $$f$$ for a spherical mirror?

Accepted Answer

$$\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}$$

Question 8

A light ray passes from air ($$n_1 = 1.00$) into water (n_2$ = 1.33) at an $$angle of $$30^\circ$$ with respect to the normal. What is the angle of refraction in the water?

Accepted Answer

$$22.0^\circ$$

Question 9

What is the index of refraction $$n of a $$material in which light travels at $$2.00 	imes 10^8$\ \mathrm{m/s}$$?

Accepted Answer

$$n = 1.50$$

Question 10

Which of the following is true about total internal reflection?

Accepted Answer

It occurs when the angle of incidence exceeds the critical angle for the interface.

Question 11

A fiber optic cable has a core with $$n_{core} = 1.50$$ and cladding with $$n_{clad} = 1.40. $$What is the critical angle for total internal reflection at the core-cladding interface?

Accepted Answer

$$	heta_c = \arcsin\left(\frac{1.40}{1.50}ight) = 69.1^\circ$$

Question 12

A $$2.0\ \mathrm{cm}$$ high object is placed $$7.10\ \mathrm{cm}$$ from a concave mirror with $$R = 10.20\ \mathrm{cm}. $$What is the height of the image?

Accepted Answer

$$h_i = -5.1\ \mathrm{cm}$$

Question 13

Which of the following best explains why optical fibers are used for telecommunications?

Accepted Answer

They allow light to travel with little loss due to total internal reflection.

Question 14

If the focal length of a convex mirror is $$-20\ \mathrm{cm}$$ and an object is placed $$60\ \mathrm{cm} in $$front of it, what is the image distance $$d_i$$?

Accepted Answer

$$d_i = -15\ \mathrm{cm}$$

Question 15

A ray of light in air strikes a pane of glass ($$n = 1.5) at$$ $$30^\circ to $$the normal. What is the angle of refraction inside the glass?

Accepted Answer

$$19.5^\circ$$

Question 16

Which of the following is a consequence of spherical aberration in mirrors?

Accepted Answer

Rays far from the principal axis do not converge at a single focal point.

Question 17

A light ray passes from water ($$n = 1.33) $$into air ($$n = 1.00) at an $$angle of incidence of $$60^\circ. $$What is the angle of refraction in air?

Accepted Answer

$$74.1^\circ$$

Question 18

Which of the following is the correct magnification equation for mirrors?

Accepted Answer

$$m = \frac{h_i}{h_o} = -\frac{d_i}{d_o}$$

Reflection and Refraction of Light: Mirrors, Lenses, and Optical Instruments

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