Waves

Question 1

what do all waves do?

Answer 1

transfer energy from one place to another

Question 2

transverse waves (2)

Answer 2

• the movement (oscillations) is 90 degrees (perpendicular) to the direction the wave travels
• the movement is up and down and the direction is sideways

Question 3

examples of transverse waves (2)

Answer 3

• ripples in a pond
• electromagnetic waves

Question 4

longitudinal waves (3)

Answer 4

• movement (oscillations) are parallel to the direction the wave travels; they’re in the same direction as the travel
• have compressions (regions where the air particles are very close together)
• sound waves travel as particles in the air move from side to side

Question 5

example of longitudinal waves

Answer 5

sound waves

Question 6

define amplitude

Answer 6

the maximum displacement from rest

(the furthest point the wave vibrates from its undisturbed position)

Question 7

define wavelength

Answer 7

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

Question 8

how is wavelength measured on longitudinal waves? (2)

Answer 8

• by measuring from one compression to the next compression
• or by measuring from one rarefaction to the next rarefaction

Question 9

define frequency

what is the unit of frequency?

Answer 9

the number of waves passing a point each second

hertz (Hz) ; 1 Hz = 1 wave per second

Question 10

define period

Answer 10

the time (in seconds) for one wave to pass a point

period = 1 divided by frequency

Question 11

electromagnetic waves (4)

Answer 11

• transverse waves
• transfer energy from the source of the waves to the absorber
• they form a continuous spectrum and all travel at the same speed in a vacuum
• the visible region of the spectrum is only a small part

Question 12

the electromagnetic spectrum (2)

Answer 12

• on the red end, the waves have:
  1. lower frequency
  2. longer wavelength
• on the violet end, the waves have:
  1. higher frequency
  2. shorter wavelength

Question 13

what is the only part of the electromagnetic spectrum that can be detected by the human eye?

Answer 13

visible light

Question 14

what is the order of the electromagnetic spectrum

Answer 14

Radiowaves
Microwaves
Infrared
Visible Light
Ultraviolet
X-Rays
Gamma Rays

Question 15

radiowaves (4)

Answer 15

examples : tv and radio

• produced by oscillations
• in electrical circuits

Question 16

microwaves (2)

Answer 16

examples : satellite communication, cooking food

Question 17

infrared (3)

Answer 17

examples : IR cameras, tv remote, cooking food

Question 18

visible light

Answer 18

examples : fibre optic communication

Question 19

ultraviolet (4)

Answer 19

examples : sun beds, check forgeries, sterilisation (water or medical equipment)

• important due to the suns rays

Question 20

x-rays (2)

Answer 20

examples : medical images, airport detection

Question 21

gamma rays (5)

Answer 21

examples : medical treatments, sterilising medical equipment

• produced when there is a change in the nucleus
• measured in sieverts (Sv)
• 1000 millisieverts = 1 sievert

Question 22

why does light change direction as it passes through water in a glass? (5)

Answer 22

• when light passes from air into glass, the velocity of light decreases
• this causes the direction of the waves to change
• the light waves now pass through the glass
• when the waves pass from the glass back into the air, their velocity increases again
• when the waves speed up, they bend away from the normal

Question 23

when can refraction happen?

Answer 23

when any wave changes speed as it passes from one medium to another

Question 24

in what case would there be no change in direction?

Answer 24

if the waves enter or leave the medium at right angles to the surface

Question 25

how does a change to the atom generate an electromagnetic wave (2)

Answer 25

• when atoms are heated, electrons move from one energy level to a higher one
• when this electron returns to its original energy level, it generates an electromagnetic wave

Question 26

how does a change to the nucleus generate an electromagnetic wave?

Answer 26

• gamma rays can be emitted from the nucleus of radioactive atoms
• once the gamma ray has been emitted, the nucleus has less energy than it had at the start

Question 27

when can radiowaves be produced?

Answer 27

when electrons oscillate in electric circuits