P6 Waves Flashcards

1
Q

How can an image appear on a ray diagram? (6)

A
  • virtual
  • real
  • upright
  • inverted
  • enlarged
  • diminished
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2
Q

Explain why a blue object appears black through a red filter

A

The filter only transmits red waves. The blue object only reflects blue waves so red is absorbed by the object and so no light is reflected by the object.

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3
Q

Give three uses of UV

A
  • tanning
  • sterilising equipment
  • energy efficient lamps
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4
Q

Describe the difference between transverse and longitudinal waves

A

in a transverse wave, the oscillations are perpendicular to the direction of energy transfer whereas in a longitudinal wave, the oscillations are parallel to the direction of energy transfer

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5
Q

What is the advantage of repeating measurements and calculating a mean?

A

Reduce effect of random errors, giving a more accurate reliable mean

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6
Q

Explain how the teacher could determine the speed of the wave if they didn’t measure the wavelength of the wave

A
  • Measure the distance travelled by a wave using a metre rule
  • Measure the time taken (for the wave to travel the measured distance) with a timer
  • Divide the distance by the time to give speed
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7
Q

Explain why using a wider ray would give less accurate results than using a narrower ray.

A

it is harder to judge where the centre of a wider ray is causing a larger uncertainty and so less accuracy

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8
Q

Explain how to get data on the angle of incidence and refraction from given angles (RPA)

A
  • place a glass block on a piece of paper and draw around the glass block then remove the block
  • draw a line at 90° (the normal) to one side of sketch
  • use a protractor to measure and then draw a line of a given angle of incidenc to the normal
  • place block back on the trace then use the ray box to shine a ray of light through the glass block at a measured angle
  • mark the incident ray (entering the glass block) and the refracted ray of light emerging from the glass block
  • remove the block and draw path of refracted ray through the block, then measure the angle of refraction with a protractor from the normal
  • repeat the procedure for a range of values of the angle of incidence
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9
Q

Describe what happens in the electrical circuit when an aerial absorbs radio waves

A

Alternating current is induced (electrons oscillate) with the same frequency as the radio wave

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10
Q

Describe two differences between radio waves and sound waves

A
  • radio waves are transverse, sound are longitudinal
  • radio waves don’t need a medium as they can travel through a vacuum
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11
Q

Explain why the study of seismic waves provides evidence for the structure of the Earth’s core

A

S-waves cannot travel through a liquid and so S-waves do not travel through the (outer) core - can understand internal structures better

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12
Q

What makes microwaves suitable for sending communications to a satellite in space?

A

Can travel through the atmosphere (not reflected by ionosphere)

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13
Q

What is a perfect black body?

A

The object is the best possible emitter of radiation: absorbs and emitts all radiation and doesn’t reflect or transmit any

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14
Q

What is the function of a microphone?

A

To convert sound (waves) into variations in current / p.d

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15
Q

Explain how the properties of X-rays make them suitable for the medical imaging of bones.

A

Can pass through soft tissue but be absorbed by bone (high frequency and short wavelengths)

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16
Q

How can the hazard of boiling water be dealt with?

A

Use slightly cooler water

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17
Q

Explain why scientists replace an old scientific model with a new model.
Include an example from Physics in your answer

A
  • New evidence may mean old models are incorrect
  • The new model will explain new evidence
  • Ie plum pudding model replaced by nuclear model
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18
Q

Explain why waves diagonally changing from deep to shallow water refract

A

Velocity is slower in shallow water so as edge of wave (front) entering shallow water at an angle slows down, part of the wave (front) in deeper water continues at a higher speed (leading to a change in direction of the wave fronts due to different velocities)

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19
Q

Explain why waves travelling parallel from deep to shallow water do not refract

A

Every point on the wave (front) enters the shallow water at the same time so every point slows down at the same time

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20
Q

RPA 9: what is a possible random error?

A

Not putting ray box in the same position each time

21
Q

State one change of apparatus to investigate diffuse reflection.

A

Using a rough irregular reflecting surface

22
Q

What is an ultrasound?

A

Sound waves with a frequency above the upper limit of human hearing range (above 20kHz)

23
Q

State two uses of ultrasound

A
  • Pre natal scanning/imaging
  • Destroying kidney stones
24
Q

State one advantage and disadvantage of X Rays

A

A: can image any part of the body

D: ionising radiation so increased risk of mutations and so can become cancerous

25
Q

Explain one possible inaccuracy when trying to measure the angle of incidence and refraction

A

The width of the light ray
which makes it difficult to judge where the centre of the ray is

26
Q

Explain reason why light is refracted as it crosses from air into glass

A

Light waves enter a more dense material so velocity decreases (light waves bend towards the normal)

27
Q

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

A

Use a (metre) ruler to measure 10 waves and then divide by 10

28
Q

If the amplitude has become smaller what has the sound become?

A

Quieter

29
Q

Explain why there is no sound in space

A

Sound cannot travel through a vacuum as needs particles to vibrate to make sound, as space is a vacuum there are no particles to vibrate and make sound

30
Q

What does the frequency of a sound wave determine (more waves are seen)?

A

Pitch

31
Q

What does amplitude of a sound wave determine?

A

Loudness

32
Q

What does amplitude of a light wave determine?

A

Brightness/ intensity of colour

33
Q

What does the frequency of a light wave determine?

A

Energy (high frequency = carry more energy)

34
Q

Do you think the ultrasound experiments on mice were justified?
Explain your answer

A

Unethical to experiment on humans so it is better to experiment on mice

35
Q

Explain what scientists should do if they find evidence that ultrasound may be harmful to human health.

A

Carry out more research to check reliability of findings

36
Q

Describe the features of ultrasound and what happens after it has entered the body

A
  • longitudinal waves
  • frequency above 20kHz (upper limit of human hearing)
  • Ultrasound is partially reflected when it meets a boundary between two different media
37
Q

Describe the features of X-rays and what happens after it has entered the body

A
  • EM transverse waves with a short wavelength and high frequency
  • Ionising radiation
  • Absorbed by bone and transmitted through skin (soft tissue)
38
Q

What is a virtual image?

A

image cannot be formed on a screen, light doesn’t actually pass through it

39
Q

Compare radio waves and sound waves (4)

A
  • radio waves are transverse, whereas sound waves are longitudinal
  • radio waves can travel through a vacuum, sound waves can’t
  • radio waves travel at the speed of light
  • radio waves have higher frequencies
40
Q

What are the primary colours of the visible light spectrum?

A

Red green and blue

41
Q

How can seismic waves be detected?

A

Using seismometers

42
Q

Explain what happens when sound waves travel from a less dense medium, to a more dense medium

A

Their speed increases, as sound requires particles to vibrate to move, there are more particles closer together in denser materials so vibrations can travel quicker and easier (by collisions)

43
Q

What is the problem with using an oscilloscope to measure sound waves?

A

Represents sound waves as transverse waves, although they are longitudinal

44
Q

What is a reflected sound wave called?

A

An echo

45
Q

What happens to wavelength and frequency if wave speed increases?

A

Wavelength increases
Frequency stays the same

46
Q

Explain why drawing a protractor on paper is better than using a normal protractor

A

Angle of incidence and reflection will be more easily read and won’t be confused

47
Q

What are the three primary colours

A

red, blue and green

48
Q

Define wavespeed

A

Speed energy is transferred through a medium (per second)

49
Q

Define amplitude

A

Maximum displacement of a point on a wave from its undisturbed position