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LV G > P12 and P13 Revision > Flashcards

P12 and P13 Revision Flashcards

To revise Chapter 12 and 13

1
Q

What do waves transfer?

A

Energy

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2
Q

What are the two types of wave?

A

Transverse and longitudinal

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3
Q

Describe a transverse wave

A

The vibrations of the wave are perpendicular** to the direction in which **energy is transferred.

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4
Q

Give some examples of transverse waves

A

Ripples on a water surface

Any wave in the electromagnetic spectrum

S waves

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5
Q

Describe a longitudinal wave

A

The vibrations of the wave are parallel** to the direction in which **energy is transferred.

Longitudinal waves show areas of compression** and **rarefaction.

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6
Q

Give some examples of longitudinal waves

A

Sound waves

Ultrasound

P waves

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7
Q

Define amplitude

A

The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed (equilibrium) position.

It shows us how much energy a wave has.

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8
Q

Define wavelength

A

The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave. Measured in meters

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9
Q

Define frequency

A

It is the number of waves that pass a point per second. Measured in hertz (Hz)

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10
Q

Define period (T)

A

Its the time for one exact wave to pass a point. Measured in seconds

T = 1 / f

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11
Q

State the wave equation with all units

A

wave speed (m/s) = frequency (Hz)× wavelength (m)

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12
Q

Describe an experiment to find the speed of sound through air

A
  1. Measure a distance of 100 m from a wall.
  2. Hit two blocks together to make a sound and start timing.
  3. Stop timing when the hear the reflected sound (echo).
  4. Divide the time recored by 2 as the sound has travelled to the wall and back again
  5. use the equation Speed = distance / time
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13
Q

Describe a method to measure the speed of ripples on a water surface.

A
  1. Set up a ripple tank.
  2. Find the wavelength by using a ruler to measure across 10 wavelengths.
  3. Divide the answer by 10 to find 1 wavelength.
  4. Use a stopwatch and count the number of waves produced in 10 seconds.
  5. Dived the answer by 10 to find the frequency.
  6. Use the equation speed = wavelength x frequency
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14
Q

What can happen to waves when they reach a boundary between two materials?

A
  1. They can be reflected
  2. They can be absorbed (this will cause a small temperature rise)
  3. They can be transmitted (they will pass through)
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15
Q

What is the law of reflection

A

The angle of incident = angle of reflection for a flat plain mirror.

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16
Q

What is refraction?

A

When a wave travels from one medium to another and changes direction.

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17
Q

Why does refraction take place?

A

The change in medium means a change in density which caused a change in speed.

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18
Q

When a substance moves from a more dense to a less dense substance, what is the affect of waves speeds, frequency and wavelength?

A
  1. Wave speed - decreases
  2. Frequency - same
  3. Wavelength - decreases
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19
Q

When a substance moves from a less dense to a more dense substance, what is the affect of waves speeds, frequency and wavelength?

A
  1. Wave speed - increases
  2. Frequency - same
  3. Wavelength - increases
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20
Q

When light slows down which direction does it refract?

A

Towards the normal

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21
Q

When light speeds up which direction does it refract?

A

Away from the normal

22
Q

Explain why light refracts as it passes from air into glass?

A

As light moves from air into glass it slows down.

The edge of the wave front entering the glass first slows down first

Part of the wave front that is still in the air continues at a higher speed causing it to travel further and to change in direction

23
Q

State the normal human hearing range

A

From 20 Hz to 20 kHz

24
Q

How do we detect sound waves?

A

Within the ear, sound waves cause the ear drum and other parts to vibrate. These vibrations are converting into an electrical signal which is passed onto the brain.

25
Q

Why do humans have a limited range of frequencies they can detect?

A

The conversion of sound waves to vibrations of solids works over a limited frequency range. This restricts the limits of human hearing.

26
Q

What is the effect of a louder sound on the ear drum?

A

larger vibrations

27
Q

What is the effect of a higher pitched sound on the ear drum?

A

Faster vibrations

28
Q

What is a ultrasound?

A

Ultrasound waves have a frequency higher than the upper limit of hearing for humans (20000 Hz)

29
Q

How can ultrasound be used for medical and industrial imaging?

A
  1. Ultrasound waves are partially reflected and partially transmitted when they meet a boundary between two different media.
  2. The time taken for the reflections to return to the detector can be measured
  3. This can be used to determine how far away such a boundary is. 2 x Distance = speed x time
30
Q

What are seismic waves

A

Waves produced by Earthquakes

31
Q

What type of waves are P-waves?

A

longitudinal

32
Q

What type of waves are S-waves?

A

Transverse

33
Q

Which earthquake waves cant travel through the liquid core?

A

S-waves as they are transverse

34
Q

What is a shadow zone?

A

An area where no p waves or s waves are detected

35
Q

What does a shadow zone show us?

A

There must be a liquid core because:

P waves are refracted at the core mantle boundary

S waves can’t travel through the liquid core

36
Q

State the waves that make up the electromagnetic spectrum, in order of increasing wavelength

A
  1. Radio waves
  2. Microwaves
  3. Infrared
  4. Visible light
  5. Ultraviolet
  6. X-rays
  7. Gamma rays
37
Q

What do all electromagnetic waves have in common?

A
  1. They are all transverse waves
  2. They can all travel through a vacuum
  3. They all travel at the speed of light through a vacuum
38
Q

How are radio waves produced?

A

By an oscillating electrical current in the transmitter. The frequency of the current will make the frequency of the radiowaves.

39
Q

What happens when radio waves are absorbed by an aerial?

A

When radio waves are absorbed they will induce create an alternating current with the same frequency as the radio wave itself

40
Q

What are the dangers of ultraviolet waves

A
  1. Can age skin prematurely
  2. Can burn skin which can lead to skin cancer
  3. Damage eyes which can lead to blindness
41
Q

What are the dangers of X-rays and gamma rays?

A

X-rays and gamma rays are ionising radiation.

Low doses can damage DNA and cause cancer

Large doses can kill cells

42
Q

State some uses of radio waves

A

television and radio, these waves stay within the earths atmosphere.

43
Q

State some uses of microwaves

A

Satellite communications eg mobile phone and satellite TV. Microwaves can travel to space and back.

Cooking food.

44
Q

State some uses of infrared

A

electrical heaters, cooking food, infrared cameras

45
Q

State some uses of visible light

A

fibre optic communications

46
Q

State some uses of ultraviolet

A

energy efficient lamps

sun tanning

security markings

47
Q

State some uses of X-rays and Gamma rays

A

medical imaging and cancer treatment.

48
Q

Describe how x-rays are used for medical imaging

A

pass through soft tissue

but are absorbed by bone

49
Q

What is the typical wavelength of an X-ray?

A

1x10^-10 m

50
Q

How does infrared and visible light travel through fibre optic cables?

A

Total internal reflection

51
Q

Which parts of the electromagnetic spectrum are ionising

A

Gamma, X-Rays and part of Ultraviolet

LV G (18 decks)

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