physics topic 6 Flashcards

(69 cards)

1
Q

describe transverse waves

A

Vibrations are perpendicular to the direction of energy transfer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Electromagnetic waves travel at what speed

A

at the speed of light
(3x10^8m/s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

give examples of transverse waves

A

Water waves,
electromagnetic (light) waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe Longitudinal waves:

A

Vibrations are parallel to the direction of energy transfer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are some examples of longitudinal waves

A

Sound waves and a type of seismic (P) wave.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is wavelength (λ)

A

distance from one point on a wave to the same
point on the next wave.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is Amplitude (m)

A

maximum displacement from its undisturbed position.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is Frequency (Hz)

A

waves per second.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is Period (s)

A

the time taken to produce one complete wave.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

give the practical for measuring the speed of sound in air

A
  1. Student A hit two cymbals together and student B started a stopwatch.
  2. When student A heard an echo she hit the cymbals together again.
  3. Student B stopped the stopwatch after timing 5 echoes.
  4. Calculate an average time for the echoes and ÷ by 2 (there and
    back)
  5. Use a measuring tape to work out the distance between students and wall
  6. Speed = Distance / Time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why does sound move faster through solids

A
  • Sound needs particles to travel
  • In a solid, particles are very close together
  • So sound is fastest through a solid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe the Ripple tank practical (investigating waves)

A

Frequency
* use a stopwatch

  • count the number of waves passing a point in 10 seconds
  • Number of waves / 10 seconds = average frequency

Wavelength

  • use a camera to freeze the image
  • use a metre rule to measure the distance between 10 waves
  • divide distance by 10 to determine average λ

Velocity
* use v=fλ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what happens when a sound wave travels from one medium to another e.g. air to water

A

the frequency remains the same.

The sound wave will travel faster in water than air.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what happens if if the frequency remains the same, as velocity increases

A

wavelength must also increase proportionally.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the Human hearing range

A

20Hz and 20,000Hz (20kHz). Anything above this is
called ultrasound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is anything’s above 20,000Hz called

A

ultrasound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe how Ultrasound waves are used for detection

A

Ultrasound waves are partially reflected
when they meet a boundary between
two different media.

The time taken for the reflections to meet
a detector can be used to determine how
far away the boundary is.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

describe some medical uses for ultrasound

A
  • Pre-natal scanning
  • Imaging (a named body part).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

why is ultrasound safe to use

A

Ultrasound does not damage (human) cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

describe Echo
location/SONAR

A

Echo location or SONAR uses high frequency sound waves to detect objects in deep water and measure water depth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what waves do earthquakes produce

A

Earthquakes produce P and S waves.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

describe P waves

A

fast longitudinal; travel at different speeds through solids and liquids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

describe S waves

A

slower transverse; cannot travel
through liquids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what can p waves and s waves lead us to understand about the earth

A

This information can be used to determine the size, density and state of the Earth’s structure. As S waves do not penetrate the outer core, they can not be used to determine whether the inner core is liquid or solid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
The study of seismic waves provided new evidence that led to discoveries about what
parts of the Earth which are not directly observable.
26
give examples of transfer of energy by electromagnetic waves
Heater - Infra red waves- Detected by heat sensors in the hand Torch - Visible light waves - Detected by cells in the retina Radio transmitter - Radio waves -Detected by the aerial in the radio
27
what does The hazard from high energy radiations depend on
depends on the dose - measured in Sieverts.
28
what harm can Ultra violet waves cause
Ultra violet waves can cause sunburn, ageing of the skin and skin cancer.
29
what harm can X rays and gamma rays cause
X rays and gamma rays are ionising radiations that can cause mutations of genes which could result in cancer.
30
list the type of electromagnet waves from Low frequency long wavelength to High frequency short wavelength
radio microwave infrared visible ultraviolet tanning beds x rays gamma rays
31
describe the application and Suitability of radio waves
Application - Television and radio Suitability - Travels long distances
32
describe the application and Suitability of microwaves
Application - Satellite communications. Cooking food Suitability - Travel through atmosphere; vibrates water molecules causing them to heat food
33
describe the application and Suitability of Infrared waves
Application - Electrical heaters, cooking food, infrared cameras Suitability - Heat energy transfer
34
describe the application and Suitability of Visible waves
Application - fibre optic communications Suitability - Travel through optic fibres and carry information
35
describe the application and Suitability of ultraviolet waves
Application - tanning beds Suitability - Skin reacts to UV light causing tanning
36
describe the application and Suitability of X-rays
Application - Medical imaging and treatment Suitability - Pass through soft tissue, penetrate materials to different extents so can produce image
37
describe the application and Suitability of Gamma rays
Application - Medical imaging and treatment Suitability - Kill tissue; tracers can produce images of internal organs.
38
what happens to light when it shines on object
Absorption, transmission and reflection
39
Absorbed light is changed into what
heat energy
40
why does A red object appears red in white light
because it only reflects the red wavelengths of light, all other colours are absorbed.
41
what do Filters do
Filters only allow light of certain wavelengths through (transmit). The rest are absorbed
42
how do colour filters work
Colour filters work by absorbing certain wavelengths (and colour) and transmitting other wavelengths (and colour).
43
what happens if If all wavelengths are reflected
the object appears white
44
what happens if all wavelengths are absorbed
the object appears black
45
Light reflecting off a smooth, flat surface produces what
specular reflection.
46
When light reflects off a rough surface produces what
diffuse reflection
47
what does it mean if something is Transparent
a material that allows objects behind it to be seen clearly as if nothing was in the way.
48
what does it mean if something is Translucent
a material that allows objects to be seen through them but not as clearly or sharply as a transparent material.
49
what does it mean if something is Opaque
a material that may or may not allow light through to the object behind. It would be difficult to tell what object is behind an opaque material.
50
what is the law of reflection
Angle of incidence (i) = angle of reflection (r)
51
why does Refraction of electromagnetic waves occur
because the wave changes speed when it enters a substance of different density.
52
why do we have a spectrum of colour
Different wavelengths of light are diffracted by different amounts, resulting in a spectrum of colour
53
describe the Light Required practical
1. Draw around the glass block on a piece of paper 2. Use the ray box to shine a ray of light through the glass block 3. Mark the ray of light entering in and emerging from the glass block 4. Join the points to show the path of the complete ray through the block 5. Draw a normal line at 90 degrees to the surface 6. Use a protractor to measure the angle of incidence and refraction 7. Increase the angle of incidence in 100 intervals – from 100 - 700 Increase accuracy: Repeat and calculate a mean Use a laser
54
Explain refraction using wave front diagrams
* Different parts of the wave front enter the glass at different times * the velocity / speed (of light) is less in glass * (so) one part of the wave front changes speed before other parts
55
how do black surfaces interact with infra red waves
Black surfaces absorb infrared waves better than white or shiny surfaces. Black surfaces also emit infrared radiation quicker than light coloured surfaces
56
why are Petrol storage tankers are painted white or polished
reflect the suns infra red heat waves.
57
describe the IR Radiation and absorption required practical
1. Get a hollow metal cube with 4 faces; matt black, shiny black, matt white, shiny silver 2. Fill cube with boiling water and measure temperature of water with a thermometer 3. Measure temperature of one of faces by placing infrared thermometer 20cm away 4. Repeat with other 3 faces 5. Record results Safety: complete the investigation standing up use (slightly) cooler water do not touch the hot cube
58
Applying radiation to electrons can do what
can excite them – move up an energy level (excitation)
59
what causes the release of radiation
If electrons move down an energy level, they release the radiation (de-excitation)
60
how do radio waves work
1. Alternating current (AC) passed through a radio transmitter 2. Oscillating electrons produce a radio wave 3. Antenna/ aerials absorbs radio waves 4. Electrons vibrate (in the aerial) 5. Inducing an alternating current (in the aerial circuit) 6. With the same frequency as the radio wave
61
Convex lenses (converging) produces what image
produce real or virtual images.
62
Concave lenses (diverging) produces what image
produce virtual images.
63
what is a Real image
A Real image is an image formed where the light rays are focused.
64
what is a Virtual image
A Virtual image is one from which the light rays appear to come from but don’t actually come from that image e.g. a mirror reflection)
65
Explain the difference between a real image and a virtual image.
* real image can be put on a screen * virtual image cannot be put on a screen / film * virtual image is imaginary * real image is formed where (real) rays cross / converge allow real image has light travelling through it * virtual image is where virtual / imaginary rays (seem to) come from * virtual image formed where virtual rays intersect / cross
66
what is A perfect black body
A perfect black body absorbs all of the radiation and also emits all radiation
67
describe how waves heat up the earth
Short wavelength radiation from the sun passes through the Earth’s atmosphere Re-radiated as long wavelength radiation. Absorbed by greenhouse gasses and reflected back to Earth heating it up; global warming.
68
how is a body kept at constant temperature
Constant temperature: Rate of radiation emission = Rate of radiation absorption
69
how does the temperate of a body increase
The temperature of a body increases when the body absorbs radiation faster than it emits radiation.