Waves And Electromagnetic Spectrum

Question 1

What are the two types of waves?

Answer 1

Transverse and longitudinal.

Question 2

What is a transverse wave?

Answer 2

A wave where the oscillations are perpendicular to the direction of energy transfer, like ripples on water.

Question 3

Give an example of a transverse wave.

Answer 3

Light waves or water surface ripples.

Question 4

What is a longitudinal wave?

Answer 4

A wave where the oscillations are parallel to the direction of energy transfer.

Question 5

Give an example of a longitudinal wave.

Answer 5

Sound waves in air.

Question 6

What features are shown in a longitudinal wave?

Answer 6

Areas of compression and rarefaction.

Question 7

What is meant by wave amplitude?

Answer 7

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

Question 8

What is wavelength?

Answer 8

The distance from one point on a wave to the equivalent point on the next wave.

Question 9

What is the frequency of a wave?

Answer 9

The number of complete waves passing a point each second.

Question 10

State the equation linking period and frequency.

Answer 10

Period (T) = 1 ÷ Frequency (f).

Question 11

What is the unit of frequency?

Answer 11

Hertz (Hz).

Question 12

What is the wave speed equation?

Answer 12

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

Question 13

How can you measure the speed of sound in air?

Answer 13

Measure the time it takes for a sound to travel a known distance and calculate speed = distance ÷ time.

Question 14

How can you measure the speed of ripples on a water surface?

Answer 14

Use a ripple tank to measure wavelength and frequency, then calculate wave speed using v = f × λ.

Question 15

What changes when a wave passes into a different medium?

Answer 15

The wave speed and wavelength can change, but the frequency stays the same.

Question 16

What happens to sound waves when they move into a denser medium?

Answer 16

They speed up.

Question 17

What happens to light waves when they move into a denser medium?

Answer 17

They slow down.

Question 18

What can happen to waves at a boundary between two materials?

Answer 18

Reflection, refraction, absorption, or transmission.

Question 19

What is reflection?

Answer 19

When a wave bounces off a surface.

Question 20

What is refraction?

Answer 20

When a wave changes direction as it passes from one medium to another due to a change in speed.

Question 21

How do you draw a ray diagram for reflection?

Answer 21

Show the incident ray, the reflected ray, and the normal line at the point of incidence; the angle of incidence = angle of reflection.

Question 22

What is absorption of a wave?

Answer 22

When the energy of the wave is absorbed by the material, often converting it to heat.

Question 23

What happens to a wave during transmission?

Answer 23

It passes through a material.

Question 24

How do sound waves travel through a solid?

Answer 24

By causing particles in the solid to vibrate.

Question 25

How do sound waves cause hearing in humans?

Answer 25

Sound waves cause vibrations in the eardrum and other parts of the ear, leading to the sensation of sound.

Question 26

Why does human hearing have a limited frequency range?

Answer 26

The conversion of sound waves to vibrations in solids (like the eardrum) only works over a certain frequency range.

Question 27

What is the normal range of human hearing?

Answer 27

20 Hz to 20,000 Hz (20 kHz).

Question 28

What is ultrasound?

Answer 28

Sound waves with frequencies above 20 kHz.

Question 29

How is ultrasound used for medical imaging?

Answer 29

Ultrasound waves are partially reflected at boundaries between different tissues, and the time taken for reflections helps create an image.

Question 30

How is ultrasound used in industry?

Answer 30

To detect flaws in materials by identifying reflections from cracks inside objects.

Question 31

What are seismic waves?

Answer 31

Waves produced by earthquakes that travel through the Earth.

Question 32

What type of wave is a P-wave?

Answer 32

A longitudinal seismic wave.

Question 33

What type of wave is an S-wave?

Answer 33

A transverse seismic wave.

Question 34

Can S-waves travel through liquids?

Answer 34

No, S-waves cannot travel through liquids.

Question 35

Can P-waves travel through solids and liquids?

Answer 35

Yes, P-waves can travel through both solids and liquids.

Question 36

How did seismic waves provide evidence for the Earth’s core structure?

Answer 36

S-waves cannot pass through the outer core, and P-waves change speed, suggesting a liquid outer core and solid inner core.

Question 37

What is echo sounding?

Answer 37

Using high-frequency sound waves to detect objects underwater and measure water depth.

Question 38

What are electromagnetic (EM) waves?

Answer 38

Transverse waves that transfer energy from the source to an absorber.

Question 39

Do all electromagnetic waves travel at the same speed in a vacuum?

Answer 39

Yes, all electromagnetic waves travel at the same speed in a vacuum (3.0 × 10⁸ m/s).

Question 40

Name the groups of the electromagnetic spectrum in order of increasing frequency.

Answer 40

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

Question 41

Which electromagnetic wave has the longest wavelength?

Answer 41

Radio waves.

Question 42

Which electromagnetic wave has the shortest wavelength?

Answer 42

Gamma rays.

Question 43

What is visible light?

Answer 43

The part of the electromagnetic spectrum that can be detected by the human eye.

Question 44

How are radio waves produced?

Answer 44

By oscillations in electrical circuits.

Question 45

How can radio waves induce an alternating current?

Answer 45

When radio waves are absorbed by a conductor, they cause electrons to oscillate, producing an AC of the same frequency.

Question 46

What happens when electromagnetic waves interact with matter?

Answer 46

They can be absorbed, reflected, transmitted, or cause ionisation depending on their energy.

Question 47

Which electromagnetic waves are ionising?

Answer 47

Ultraviolet, X-rays, and gamma rays.

Question 48

What can exposure to ultraviolet radiation cause?

Answer 48

Skin aging and increased risk of skin cancer.

Question 49

What can X-rays and gamma rays cause in the body?

Answer 49

Mutation of genes and cancer.

Question 50

What is radiation dose measured in?

Answer 50

Sieverts (Sv).

Question 51

What are the dangers associated with X-rays and gamma rays?

Answer 51

They are highly ionising and can damage living tissue and cause cancer.

Question 52

Give two uses of radio waves.

Answer 52

Television and radio communication.

Question 53

Give two uses of microwaves.

Answer 53

Satellite communication and cooking food.

Question 54

Give two uses of infrared radiation.

Answer 54

Electrical heaters and infrared cameras.

Question 55

Give a use of visible light.

Answer 55

Fibre optic communications.

Question 56

Give two uses of ultraviolet light.

Answer 56

Energy-efficient lamps and sun tanning.

Question 57

Give two uses of X-rays.

Answer 57

Medical imaging (bone fractures) and security scanning.

Question 58

Give a use of gamma rays.

Answer 58

Treatment of cancer (radiotherapy) and sterilising medical equipment.

Question 59

Why is each electromagnetic wave suited to its use?

Answer 59

Due to its wavelength, energy, and ability to penetrate or transfer energy effectively (e.g., X-rays can pass through soft tissue but are absorbed by bones).