Question 1

Which of the following statements correctly describes the relationship between the electric and magnetic fields in an electromagnetic wave propagating in a vacuum?

Accepted Answer

The electric and magnetic fields are orthonormal to each other and both are perpendicular to the direction of propagation.

Question 2

A radio wave and a gamma ray are both electromagnetic waves. Which of the following is true about their wavelengths and frequencies?

Accepted Answer

Radio waves have longer wavelengths and lower frequencies than gamma rays.

Question 3

The speed of light in a vacuum is denoted by $$c. $$Which equation correctly relates the magnitudes of the electric field $$E$$ and the magnetic field $$B in an $$electromagnetic wave?

Accepted Answer

$$E = cB$$

Question 4

Which phenomenon allows fiber optic cables to transmit light signals over long distances without significant loss?

Accepted Answer

Total internal reflection

Question 5

A beam of light passes from air ($$n = 1.00) $$into water ($$n = 1.33) at an $$angle of $$30^	ext{o} to $$the normal. 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

$$\$$theta_2$$ = 22.1^	ext{o}$$

Question 6

Which of the following best explains why sunglasses with polarizing lenses reduce glare from horizontal surfaces?

Accepted Answer

They block light polarized in the horizontal direction, which is predominantly reflected from flat surfaces.

Question 7

A surgical laser emits a coherent beam of light. Which property distinguishes this laser light from the light emitted by an incandescent bulb?

Accepted Answer

Laser light is coherent and has a narrow spectral window.

Question 8

Which of the following is a correct statement about the propagation of electromagnetic waves?

Accepted Answer

Electromagnetic waves can propagate in a vacuum without a medium.

Question 9

A light ray travels from glass ($$n = 1.52) $$into air ($$n = 1.00). $$What is the minimum angle of incidence in the glass for total internal reflection to occur? (Use $$\sin 	heta_c = n_2$/n_1$)

Accepted Answer

$$	heta_c = 41.1^	ext{o}$$

Question 10

Which of the following best describes specular reflection?

Accepted Answer

Reflection from a highly polished, planar surface, resulting in orderly reflected rays.

Question 11

A photon flux from a powerful laser can slow molecules to a complete stop. What is this phenomenon called?

Accepted Answer

Laser cooling

Question 12

Which equation correctly expresses Snell's Law for the refraction of light at the boundary between two media?

Accepted Answer

$$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2$$

Question 13

Which of the following is NOT a property of electromagnetic waves?

Accepted Answer

They require a medium to propagate.

Question 14

If a light wave passes through two polarizers oriented at $$90^	ext{o} to $$each other, what happens to the intensity of the transmitted light?

Accepted Answer

It is completely blocked.

Question 15

Which real-world application relies on total internal reflection for its operation?

Accepted Answer

Fiber optic communication

Question 16

A person wearing a black t-shirt on a sunny day feels warmer than someone wearing a white t-shirt. Which property of electromagnetic waves explains this observation?

Accepted Answer

Black t-shirts absorb more electromagnetic energy, especially in the infrared and visible spectrum.

Question 17

Which of the following best describes the ray approximation in optics?

Accepted Answer

It models light as rays perpendicular to wave fronts, valid for geometric optics.

Question 18

Why do insects see patterns on flowers in ultraviolet light that humans cannot see?

Accepted Answer

Insects can detect ultraviolet wavelengths, which reveal patterns invisible to humans.

Question 19

Which of the following statements about the electromagnetic spectrum is correct?

Accepted Answer

Gamma rays have the highest frequency and energy.

Question 20

A light ray passes from air into diamond ($$n = 2.417). If $$the angle of incidence in air is $$45^	ext{o}$$, what is the angle of refraction in diamond? (Use Snell's Law: $$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2)$$

Accepted Answer

$$\$$theta_2$$ = 16.8^	ext{o}$$

Electromagnetic Waves: Study Notes (Chapter 23, College Physics)

Study Guide - Practice Questions

Study Guide - Flashcards