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Question 1

Wavelength

Answer 1

Distance between 1 point on a wave and the same point on the next wave

Question 2

Amplitude

Answer 2

Distance from equilibrium line to maximum displacement (crest or trough)

Question 3

Frequency

Answer 3

Number of waves that pass a single point per second

Question 4

Period

Answer 4

Time taken for a whole wave to completely pass a single point

Question 5

Relationship between frequency and velocity

Answer 5

Directly proportional

Question 6

Relationship between wavelength and velocity

Answer 6

Directly proportional

Question 7

Relationship between period and frequency

Answer 7

Inversely proportional

Question 8

Transverse waves

Answer 8

Have peaks and troughs, vibrations are straight angled to the direction of travel.

Question 9

Transverse waves examples

Answer 9

Light, EM, water ripples

Question 10

Longitudinal waves

Answer 10

Compressions and rare fractions, vibrations in same direction as direction of travel

Question 11

Longitudinal waves example

Answer 11

Sound waves, ultrasound waves

Question 12

What is a medium

Answer 12

Substance that waves pass through (air, water, glass)

Question 13

how does frequency change with medium

Answer 13

It doesn’t

Question 14

What is optical density (density of a medium)

Answer 14

measures the ability of an object to slow or delay the transmission of light

Not necessarily physical density

Question 15

Passing into a denser medium

Answer 15

The speed of the wave decreases, so wavelength decreases
Speed decreases because
it is travelling through a more dense medium, so it can’t travel fast
Energy of the wave must be constant because of conservation of energy. So this means frequency stays the same, colour is dependant on frequency so colour stays the same

Question 16

What can happen at an interface, and what does it depend on?

Answer 16

Reflection, transmission or absorption , depends on the electrons in the material

Electrons can only absorb certain amounts of energy which is directly related to frequency (higher f= more energy). So light of diff frequencies interact diff

Question 17

Reflection

Answer 17

Waves will reflect of a flat surface, the smoother the surface, the stronger the reflected wave is

Rough surfaces scatter the light in all directions, so appear matt and not reflective

Angle of incidence = angle of reflection

Question 18

Transmission

Answer 18

Waves will pass thru a transparent material. The more transparent, the more light will pass thru the material. It could still refract, but the process of passing thru the material and still emerging is transmission

Question 19

Absorption

Answer 19

If the frequency of a light matches the difference in energy less of the electrons, the light will be absorbed by the electrons and not re-emitted except over time as heat

If a material appears a certain colour, only that colour light has been reflected, and the rest of the frequencies i visible light have been absorbed

Question 20

What happens when ultrasound reaches a boundary between 2 media

Answer 20

They are partially reflected back. The remainder of the waves continue and pass through. A receiver next to the emitter can record the reflected waves

Question 21

In ultrasound what can the time between emission and detection show

Answer 21

The distance from the source at which they were reflected, as the speed of the wave is constant

Question 22

When will light reflect

Answer 22

If the object is opaque and not absorbed by the material. The electrons will absorb the light energy, then remit it as a reflected wave

Question 23

What can ultrasound be used for

Answer 23

Imaging under surfaces (foetus scan, finding cracks in metal)

Question 24

Sonar

Answer 24

Waves undergo the same processes atps ultrasound, but on a larger sale

Question 25

How does the ear work

Answer 25

1) outer ear collects sounds and channels it down the ear canal- it acts as an air pressure wave 2) the sound waves hit the eardrum causing it to vibrate at the same frequency as the sound as the incoming pressure waves reach it (compressions force the eardrum inward, rarefactions force the eardrum outward) 3) the small bones connected to the eardrum also vibrate at the same frequency. They act as an amplifier of the sound waves and transfer the compression waves to the fluid in the cochlea 4) as the fluid moved small hairs in the cochlea move too, each hair respond to different frequencies, so they move differently 5) each hair is attached to a nerve cell, so a specific frequency is received. This triggered an electrical impulse to the brain, which interpreted this as sound

Question 26

Limitations of frequency range

Answer 26

20-20000 Hz As you get older you hear less due to changes in inner ear You can only hear certain frequencies due to adaptations

Question 27

What is a ripple tank

Answer 27

Shallow glass tank containing a fluid with a needle or paddle which oscillates, producing water waves at a chosen frequency.

Question 28

What would happen if you shone light thru a ripple tank

Answer 28

Dark and light patches would appear underneath it as light passes thru wave crests and troughs Troughs appear light Crests appear dark - greater depth of water so light is scattered the most

Question 29

How to calculate frequency in ripple tank

Answer 29

Count number of times dark (max) passes thru point in a minute, then driving by 60

Question 30

How to measure wavelength in ripple tank

Answer 30

Using a strobe light at same frequency as the waves, so the pattern of waves appears fixed on the screen.

Question 31

How can reflection be shown in a ripple tank

Answer 31

Using an obstruction

Question 32

How can refraction be shown in a ripple tank

Answer 32

By placing a thick glass sheet on part of the tank floor. The depth of the water becomes shallower in that area. Since wave speed depends on depth, the ripples show down in the shallow area

Question 33

Evidence of particles in waves

Answer 33

Particles travel perpendicular to the direction of the waves travel If a ping pong ball is placed in a ripple tank, it doesn’t get carried by the wave, it just moves up and down, not in the direction of the wave This proves evidence that it is the wave travelling, not the water itself

Question 34

What is the velocity of EM in space (vacuum)

Answer 34

3 x 10 ^8 m/s

Question 35

Why don’t EM waves need particles to move to transfer energy

Answer 35

They are transverse waves

Question 36

Frequency wavelength relationship for EM waves

Answer 36

Speed is constant for all EM waves, therefore as wavelength decreases, frequency must increase. As frequency increases, the energy of the wave increases

Question 37

EM spectrum order

Answer 37

RMIVUXG

Question 38

Radio waves uses

Answer 38

Communications

Question 39

Microwaves uses

Answer 39

Cooking

Question 40

Visible waves uses

Answer 40

Short range communication, remote controls

Question 41

Visible waves uses

Answer 41

To illuminate things so we can see them

Question 42

UV wave uses

Answer 42

Sterilisation, as it kills bacteria

Question 43

X-ray wave uses

Answer 43

To see thru soft tissue and look at skeleton

Question 44

Gamma wave uses

Answer 44

Kill cancer cells in radiotherapy

Question 45

Which EM waves are dangerous

Answer 45

UV, X-ray and gamma, as they have a small wavelength, high frequency and therefore high energy . The high energy means they can cause cells to mutate- cancer