Question 1

Which of the following best describes the relationship between the electric field (E), magnetic field (B), and the direction of propagation in an electromagnetic wave?

Accepted Answer

E and B are perpendicular to each other and both are perpendicular to the direction of propagation.

Question 2

A microwave oven operates at a frequency of $$1 	imes 10$$^{10}$$ Hz. What is the approximate wavelength of these microwaves?

Accepted Answer

On the order of centimeters

Question 3

Which equation correctly relates the speed of light $$c$$, the permittivity of free space $$\$$varepsilon_0$$, and the permeability of free space $$\$$mu_0$$?

Accepted Answer

$$c = \frac{1}{\sqrt{\$$varepsilon_0$$ \mu_0$}}$$

Question 4

If the electric field amplitude in an electromagnetic wave is doubled, by what factor does the intensity change?

Accepted Answer

It increases by a factor of four

Question 5

A distant galaxy emits a green spectral line at $$\lambda = 500 nm$$, but it is observed on Earth at $$\lambda_{obs} = 500.7 nm. $$What can you conclude about the galaxy's motion?

Accepted Answer

It is moving away from us

Question 6

Which of the following statements about electromagnetic waves is FALSE?

Accepted Answer

They require a medium to propagate.

Question 7

A radio wave has a frequency of $$1 	imes 10^5$ Hz. What is its approximate wavelength?

Accepted Answer

On the order of kilometers

Question 8

Which property of electromagnetic waves allows astronomers to determine the velocity of distant galaxies?

Accepted Answer

The Doppler shift of spectral lines

Question 9

What is the effect on the speed of light from a star moving away from Earth?

Accepted Answer

It remains unchanged

Question 10

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

Accepted Answer

Blue light is scattered more efficiently by air molecules than red light.

Question 11

A light ray passes from air ($$n=1.0) $$into glass ($$n=1.52) at an $$angle of $$30^\circ to $$the normal. Which law allows you to calculate the angle of refraction?

Accepted Answer

Snell's Law

Question 12

Which of the following is TRUE about the image formed by a flat mirror?

Accepted Answer

It is virtual and upright.

Question 13

A person stands 3 m in front of a flat mirror. How far behind the mirror does the image appear?

Accepted Answer

3 m

Question 14

What is the minimum height of a flat mirror required for a person to see their entire body?

Accepted Answer

Half their height

Question 15

Which of the following best describes total internal reflection?

Accepted Answer

It occurs when the angle of incidence exceeds the critical angle and all light is reflected back into the denser medium.

Question 16

A fish is swimming at a depth of 3 m below the surface of a lake ($$n_{water} = 1.33). $$What is the apparent depth as viewed from above the water ($$n_{air} = 1.0$$)?

Accepted Answer

$$2.25 m$$

Question 17

Which of the following is a correct statement about the law of reflection?

Accepted Answer

The angle of incidence equals the angle of reflection.

Question 18

Which of the following best explains why sunsets appear red?

Accepted Answer

Blue light is scattered out of the line of sight, leaving mostly red light to reach the observer.

Question 19

A convex mirror has a focal length of $$1.5 m. A $$patient stands $$5.0 m $$from the mirror. What is the sign of the image distance according to the sign convention for mirrors?

Accepted Answer

Negative, because the image is virtual.

Question 20

Which of the following is TRUE about the image formed by a diverging (concave) lens?

Accepted Answer

It is always virtual, upright, and reduced.

Electromagnetic Waves and Geometric Optics: College Physics Study Notes

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