Question 1

Which statement best describes the law of reflection for a light ray striking a flat mirror?

Accepted Answer

The angle of incidence is equal to the angle of reflection: $$	heta_i = 	heta_r.$$

Question 2

A person stands 2 meters in front of a flat mirror. How far is the image of the person from the person?

Accepted Answer

4 meters

Question 3

Which type of reflection occurs when light strikes a rough surface?

Accepted Answer

Diffuse reflection

Question 4

A concave mirror has a radius of curvature $$R = 40\ \mathrm{cm}. $$What is its focal length $$f$$?

Accepted Answer

$$f = 20\ \mathrm{cm}$$

Question 5

An object is placed $$30\ \mathrm{cm} in $$front of a concave mirror with a focal length of $$15\ \mathrm{cm}. $$Where is the image formed?

Accepted Answer

At $$30\ \mathrm{cm} in $$front of the mirror, using $$\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}$$, $$d_i = 30\ \mathrm{cm}$$

Question 6

Which statement about virtual images formed by mirrors is correct?

Accepted Answer

Virtual images are always upright and appear behind the mirror.

Question 7

A car's side mirror is convex. What is the effect on the image seen by the driver?

Accepted Answer

The image appears smaller and farther away than it actually is.

Question 8

Light travels from air ($$n_1 = 1.00$) into water (n_2$ = 1.33) at an $$incident angle of $$30^\circ. $$What is the angle of refraction in the water? (Use Snell's Law: $$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2)$$

Accepted Answer

$$\$$theta_2$$ = 22^\circ$$

Question 9

Which phenomenon allows fiber optic cables to transmit light with minimal loss?

Accepted Answer

Total internal reflection

Question 10

A beam of white light passes through a prism. Which color is bent the most and why?

Accepted Answer

Blue, because it has the shortest wavelength and highest index of refraction

Question 11

An object is placed $$10\ \mathrm{cm} in $$front of a convex mirror with a focal length of $$-20\ \mathrm{cm}. $$Where is the image formed?

Accepted Answer

At $$-6.7\ \mathrm{cm}$$ behind the mirror

Question 12

What is the magnification $$M of an $$image formed by a mirror, given by the formula $$M = -\frac{d_i}{d_o}$$, if the object distance $$d_o = 15\ \mathrm{cm}$$ and the image distance $$d_i = 30\ \mathrm{cm}$$?

Accepted Answer

$$M = -2$$

Question 13

Which of the following best explains why you see your reflection in a shiny metal spoon but not in a piece of paper?

Accepted Answer

Paper causes diffuse reflection, while metal causes specular reflection.

Question 14

If the speed of light in a medium is $$2.0 	imes 10^8$\ \mathrm{m/s}$$, what is the index of refraction $$n of $$the medium? (Speed of light in vacuum $$c = 3.0 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$n = 1.5$$

Question 15

A ray of light strikes a glass surface ($$n = 1.5) at an $$angle of $$60^\circ$$ from the normal. What is the angle of reflection?

Accepted Answer

$$60^\circ$$

Question 16

Which condition is necessary for total internal reflection to occur?

Accepted Answer

Light must travel from a medium with higher to lower index of refraction and the incident angle must exceed the critical angle.

Question 17

A student shines a laser at $$45^\circ$$ into a tank of water ($$n = 1.33) $$from air ($$n = 1.00). $$What happens to the direction of the light?

Accepted Answer

It bends towards the normal.

Question 18

If an object is placed inside the focal length of a concave mirror, what type of image is formed?

Accepted Answer

A virtual, upright image

Question 19

A beam of light contains both red and blue wavelengths and enters glass at an incident angle. If the index of refraction for blue light is $$n_b = 1.53$$ and for red light is $$n_r = 1.51$$, which color bends more and why?

Accepted Answer

Blue, because it has a higher index of refraction and shorter wavelength

Mirrors and the Behavior of Light: Geometric Optics and Reflection

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