Q: A beam of light in water ($$n = 1.33) $$strikes the water-air interface. What is the critical angle for total internal reflection?

$$\theta_c = \arcsin\left(\frac{1}{1.33}\right) \approx 48.8^\circ$$

Question 1

Which of the following statements best describes the ray model of light?

Accepted Answer

Light travels in straight lines and rays can cross without interacting.

Question 2

A camera obscura forms an image of a tree outside. If the distance from the tree to the aperture is $$d_o = 10\ \mathrm{m}$$, the distance from the aperture to the image is $$d_i = 2\ \mathrm{m}$$, and the tree's height is $$h_o = 5\ \mathrm{m}$$, what is the height of the image $$h_i$$?

Accepted Answer

$$h_i = 1\ \mathrm{m}$$

Question 3

Which equation correctly relates the speed of light in a medium to the index of refraction?

Accepted Answer

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

Question 4

A laser pointer beam reflects off a flat mirror. If the angle of incidence is $$30^\circ$$, what is the angle of reflection?

Accepted Answer

$$30^\circ$$

Question 5

A light ray passes from air ($$n_1 = 1.00$) into glass (n_2$ = 1.50) at an $$angle of incidence $$\$$theta_1$$ = 40^\circ. $$What is the angle of refraction $$\$$theta_2$$ in the glass? (Use n_1$ \sin \$$theta_1$$ = n_2$ \sin \$$theta_2$$)

Accepted Answer

$$\$$theta_2$$ = 25.4^\circ$$

Question 6

Which of the following is a necessary condition for total internal reflection to occur?

Accepted Answer

The light must travel from a medium with higher index of refraction to one with lower index of refraction.

Question 7

A beam of light in water ($$n = 1.33) $$strikes the water-air interface. What is the critical angle for total internal reflection?

Accepted Answer

$$	heta_c = \arcsin\left(\frac{1}{1.33}ight) \approx 48.8^\circ$$

Question 8

When light passes from air into water, which of the following quantities remains unchanged?

Accepted Answer

Frequency

Question 9

A narrow beam of light in air ($$n_1 = 1.00$) strikes a transparent material at 63$$^\circ$$ to the surface and is transmitted at 79$$^\circ$$ to the surface. What is the index of refraction of the material?

Accepted Answer

$$n_2 = 0.91$

Question 10

Which of the following best explains why you can see a laser beam from the side only when there are particles in the air?

Accepted Answer

Light rays are scattered by particles, redirecting some rays toward your eye.

Question 11

A person stands 1.5 m in front of a plane mirror. If the person is 170 cm tall and their eyes are 10 cm below the top of their head, what is the maximum height above the floor for the bottom of the mirror so that the person can see their feet?

Accepted Answer

0 m (mirror touches floor)

Question 12

Which of the following statements about virtual images in a plane mirror is correct?

Accepted Answer

The image appears to be the same distance behind the mirror as the object is in front.

Question 13

A narrow beam of light moves from water ($$n = 1.33) $$into glass ($$n = 1.50) at an $$angle of incidence of $$30^\circ. $$What is the angle of refraction in the glass?

Accepted Answer

$$26.2^\circ$$

Question 14

Which of the following best describes the difference between specular and diffuse reflection?

Accepted Answer

Specular reflection occurs on smooth surfaces and produces clear images, while diffuse reflection occurs on rough surfaces and scatters light in many directions.

Question 15

If the wavelength of light in medium 1 is $$\$$lambda_1$$ and in medium 2 is $$\$$lambda_2$$, and their indices of refraction are $$n_1$$ and $$n_2$$ respectively, which equation is correct?

Accepted Answer

$$\frac{\$$lambda_2$$}{\$$lambda_1$$} = \frac{n_1$}{n_2$}$$

Question 16

A fibre optic cable relies on which optical phenomenon to transmit light efficiently over long distances?

Accepted Answer

Total internal reflection

Question 17

A light ray in glass ($$n = 1.5) $$strikes the glass-air interface at $$60^\circ to $$the normal. What does Snell’s Law predict for the angle of refraction in air?

Accepted Answer

No refraction occurs; total internal reflection happens because $$\sin(\$$theta_2$$) \u003e 1.$$

Question 18

Which of the following is true about the formation of an image in a camera obscura?

Accepted Answer

The image is inverted because rays from the top of the object form the bottom of the image.

Ray Optics: Reflection, Refraction, and Image Formation

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