Waves (paper 2)

Question 1

What is a wave?

Answer 1

a transfer of energy from one point to another

Question 2

name the two types of waves and there definitions

Answer 2

• Mechanical waves ~ waves that vibrate through a medium (a substance)
• Electromagnetic waves ~ waves which can travel through a vacuum (no medium is needed)

Question 3

transverse wave

Answer 3

The oscillations of a transverse wave are perpendicular to the direction in which the waves transfer energy

Question 4

longitudinal wave

Answer 4

The oscillations of a longitudinal wave are parallel to the distance in which the waves transfer energy

Question 5

what type of waves are electromagnetic waves

Answer 5

• transverse

Question 6

what type of waves are mechanical waves

Answer 6

• transverse
• longitudinal

Question 7

What is amplitude?

Answer 7

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

Question 8

what is the wavelength of a wave?

Answer 8

the distance from a point on the wave to the equivalent point on the adjacent wave

Question 9

what is frequency?

Answer 9

number of waves passing a fixed point per second

Question 10

What is the frequency equation?

Answer 10

Period (seconds) = 1/frequency

T (s) = 1/F (Hz)

Question 11

What is wave speed?

Answer 11

distance travelled by each wave per second

Question 12

What is the wave speed equation?

Answer 12

Wave speed = frequency x wavelength

V (m/s) = f (Hz) x λ (m)

Question 13

What are sound waves?

Answer 13

Vibrations that travel through a medium

Question 14

What are ultrasound waves?

Answer 14

waves above the frequency of 20kH^2 (20000H^2)

Question 15

What is the equation for distance?

Answer 15

Distance = speed x time

Question 16

How are seismic waves produced?

Answer 16

They are produced in an earthquake. They spread out from the epicentre

Question 17

What is the epicenter?

Answer 17

The nearest point on the surface to where the earthquake originates.

Question 18

What types of waves do earthquakes create?

Answer 18

• primary seismic waves (P-waves) that are longitudinal
• secondary seismic waves (S-waves) that are transverse

Question 19

How fast do electromagnetic waves travel in a vacuum?

Answer 19

3x10^8m/s

Question 20

List the electromagnetic spectrum in stating the order of increasing frequency and increasing wavelength

Answer 20

increasing frequency —->
Radio ~ Microwave ~ Infrared ~ visible ~ ultraviolet ~ x-ray ~ gamma
<—-increasing wavelength

Question 21

uses of infrared

Answer 21

• optical fibers
• remote controls
• ovens
• thermal imaging

Question 22

Uses of microwaves

Answer 22

• Navigation
• cooking
• drying
• mobile phones

Question 23

uses of visible light

Answer 23

• photosynthesis
• optical fibers
• torches
• cameras

Question 24

What are gamma rays 2 main uses

Answer 24

• killing harmful bacteria in food or on surgical equipment
• cancer treatment

Question 25

What is the main use of x-rays

Answer 25

medical imaging

Question 26

What is ionisation?

Answer 26

When an atom loses an electron. One cause of this is x-rays or gamma rays passing through a substance. If ionisation happens to living cells it can damage cells and potentially cause cancer

Question 27

How can x-rays be blocked?

Answer 27

- bones - teeth -metal inside body

Question 28

How can you x-ray soft tissue organs?

Answer 28

By filling them with a contrast medium that absorbs x-rays

Question 29

define peak

Answer 29

highest point above the rest position

Question 30

define trough

Answer 30

lowest point

Question 31

Explain the changes in air pressure caused by longitudinal waves in regions of compression and rarefaction.

Answer 31

- compression ~ the air particles are close together resulting in high pressure - rarefaction ~ air particles are spread further apart leading to low pressure

Question 32

approximate range of wavelengths

Answer 32

10^-15 m – 10^4 m

Question 33

what is the only part of the electromagnetic spectrum that our eyes can detect?

Answer 33

visible light

Question 34

from the electromagnetic spectrum, give the name and use of a radiation of lower frequency than light

Answer 34

- microwave - cooking

Question 35

name 3 types of electromagnetic spectrum radiation which has more energy than infrared

Answer 35

- visible light - x-ray - gamma ray

Question 36

1. the wavelength of infrared is... the wavelength of microwaves 2. the frequency of microwaves is... the frequency of infrared 3. the speed of microwave in a vacuum is... the speed of infrared in a vacuum

Answer 36

1. less than 2. less than 3. the same as

Question 37

X-rays can be dangerous to people because X-rays are... radiation

Answer 37

ionising

Question 38

a student finds it difficult to measure ripples on the surface of some water in a ripple tank because the ripples are moving. Suggest and explain what the student could do to make the measurement easier.

Answer 38

- student can use strobe light - when the strobe light matches the length of the waves the waves fronts will appear stationary

Question 39

uses of ultrasound

Answer 39

- breaking kidney stones - cleaning jewellery

Question 40

describe how the wavelength of the water waves in a ripple tank can be measured accurately

Answer 40

measure length of the number of waves then divide by the number of the waves

Question 41

state the name given to reflected sound waves

Answer 41

echo

Question 42

state one industrial use for ultrasound

Answer 42

cleaning

Question 43

state one medical use for ultrasound

Answer 43

pre-natal scanning