Unit 1 - Waves In Communication

Question 1

What is constructive interference?

Answer 1

When two waves meet in phase and combine to make a larger wave. The waves must be coherent (same frequency and constant phase difference).

Question 2

What is destructive interference?

Answer 2

When two waves meet out of phase and cancel each other out, reducing overall amplitude.

Question 3

What is amplitude?

Answer 3

The maximum displacement of a point on a wave from its equilibrium position.

Question 4

What is displacement in a wave?

Answer 4

The distance and direction a point on the wave is from its equilibrium position at a specific moment.

Question 5

What is wavelength?

Answer 5

The distance between two consecutive points in phase on a wave, such as crest to crest.

Question 6

What is frequency?

Answer 6

The number of complete wave cycles passing a point per second, measured in hertz (Hz).

Question 7

What is the period of a wave?

Answer 7

The time taken for one complete cycle of a wave, calculated as T = 1/f.

Question 8

What is the equation for wave speed?

Answer 8

Wave speed = frequency × wavelength (v = f × λ)

Question 9

What is wave speed?

Answer 9

The distance a wave travels per second, measured in meters per second (m/s).

Question 10

What is a transverse wave?

Answer 10

A wave where particle displacement is perpendicular to the direction of wave propagation.

Question 11

Give three examples of transverse waves.

Answer 11

Light waves, water waves, and seismic S-waves.

Question 12

What is a longitudinal wave?

Answer 12

A wave where particle displacement is parallel to the direction of wave propagation.

Question 13

Give two examples of longitudinal waves.

Answer 13

Sound waves and seismic P-waves.

Question 14

What are compressions and rarefactions?

Answer 14

Compressions are areas where particles are close together; rarefactions are areas where particles are spread apart e.g. found in longitudinal waves.

Question 15

Are electromagnetic waves transverse or longitudinal?

Answer 15

Electromagnetic waves are transverse.

Question 16

Are sound waves transverse or longitudinal?

Answer 16

Sound waves are longitudinal.

Question 17

What does ‘coherence’ mean in wave physics?

Answer 17

Two waves are coherent if they have the same frequency and a constant phase difference.

Question 18

What is reflection?

Answer 18

When a wave hits a surface, like a wall or mirror and bounces back into the original direction it came from instead of passing through.

Question 19

What is refraction?

Answer 19

The bending of a wave as it passes from one medium to another due to a change in its speed.

Question 20

What is diffraction?

Answer 20

The spreading of waves when they pass through a gap or around an obstacle.

Question 21

What is interference?

Answer 21

The phenomenon where two waves superpose to form a resultant wave of greater, lower, or the same amplitude.

Question 22

What are electromagnetic waves?

Answer 22

Waves that consist of oscillating electric and magnetic fields and can travel through a vacuum at the speed of light.

Question 23

What type of wave is every EM wave?

Answer 23

Transverse.

Question 24

What is the speed of all EM waves in a vacuum?

Answer 24

Approximately 3.00 × 10^8 meters per second (the speed of light).

Question 25

List the EM spectrum in order of increasing frequency.

Answer 25

Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.

Question 26

Which EM waves are used in remote controls?

Answer 26

Infrared waves.

Question 27

Which EM wave can cause sunburn?

Answer 27

Ultraviolet (UV) rays.

Question 28

Which EM wave is used for medical imaging?

Answer 28

X-rays.

Question 29

Which EM wave is used to kill cancer cells?

Answer 29

Gamma rays.

Question 30

Which EM wave has the longest wavelength?

Answer 30

Radio waves.

Question 31

Which EM wave has the highest frequency and energy?

Answer 31

Gamma rays.

Question 32

How are waves used in communication?

Answer 32

Waves (usually EM waves like radio or microwaves) carry information by being modulated and transmitted over distances to receivers.

Question 33

What is modulation in communication?

Answer 33

Modulation is the process of changing a wave’s properties (like amplitude or frequency) to encode information.

Question 34

What types of waves are used in wireless communication?

Answer 34

Radio waves, microwaves, and infrared — all EM waves.

Question 35

Why are microwaves used for satellite communication?

Answer 35

Because they can penetrate the Earth's atmosphere and are not easily scattered.

Question 36

What limits the range of radio waves?

Answer 36

Interference, obstacles, and how strongly the signal is transmitted.

Question 37

How are radio waves used in communication?

Answer 37

They are used to transmit radio and television signals over long distances.

Question 38

What is the role of optical fibers in communication?

Answer 38

They transmit light signals over long distances with minimal loss, used in internet and telephone services.

Question 39

What are compressions and rarefactions?

Answer 39

Compressions are areas where particles are close together; rarefactions are areas where they are spread apart — found in longitudinal waves.

Question 40

What is meant by 'in phase' in wave physics?

Answer 40

When two points on different waves have the same displacement and are moving in the same direction.

Question 41

What is meant by 'out of phase' in wave physics?

Answer 41

When two points on different waves have opposite displacements, such as a crest meeting a trough.

Question 42

What is visible light used for in technology?

Answer 42

Used in cameras, microscopes, fiber optics, and human vision.

Question 43

What is infrared radiation used for?

Answer 43

Used in thermal imaging, remote controls, and night vision devices.

Question 44

What are microwaves also used for besides communication?

Answer 44

Used in cooking (microwave ovens) and radar systems.

Question 45

What happens to wavelength when a wave enters a denser medium?

Answer 45

The wavelength decreases while frequency remains the same.

Question 46

What happens to wave speed in a denser medium (for most mechanical waves)?

Answer 46

The speed usually decreases due to increased resistance.

Question 47

Which type of wave requires a medium to travel?

Answer 47

Longitudinal waves (e.g., sound) require a medium.

Question 48

Can transverse waves travel through a vacuum?

Answer 48

Yes, like electromagnetic waves (light, radio, etc.).

Question 49

How do you rearrange the wave speed formula to find frequency?

Answer 49

Frequency = wave speed ÷ wavelength (f = v ÷ λ)

Question 50

How do you rearrange the wave speed formula to find wavelength?

Answer 50

Wavelength = wave speed ÷ frequency (λ = v ÷ f)