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Physics > P6 > Flashcards

P6 Flashcards

1
Q

What are the 2 types of waves?

A

Transverse and longitudinal

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2
Q

What are transverse waves?

A

When the oscillations are perpendicular (at a right angle) to the direction of energy transfer.

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3
Q

What are longitudinal waves?

A

When the oscillations are parallel to the direction of energy transfer

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4
Q

What do all longitudinal waves require in order to travel?

A

A medium

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5
Q

Do all transverse waves require a medium to travel in?

A

No

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6
Q

What do all waves transfer from one place to another?

A

Energy

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7
Q

In a sound wave what is the name of the area/region where air particles are close together?

A

Compressions

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8
Q

In a sound wave what is the name of the area/region where air particles are spread out?

A

Rarefactions

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9
Q

What 3 things happen to waves?

A

They are either absorbed, transmitted or reflected.

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10
Q

What do transmissions sometimes lead to?

A

Refraction → a change of direction

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11
Q

What are the 7 types of electromagnetic waves. (In order of highest frequency

A

Gamma, X-ray, ultraviolet (UV), visible, infrared, microwave, radio waves

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12
Q

What are similarities of EM waves?

A
  • transverse
  • travel at the same speed through air or a vacuum
  • they are vibrations of electric and magnetic fields
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13
Q

what are differences of EM waves

A
  • travel at different speeds in different materials
  • vary in wavelength
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14
Q

why is there such a large range of frequencies in EM waves?

A

because EM waves are generated by a variety of changes in atoms and their nuclei

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15
Q

which EM wave has the highest / least frequency?

A

Gamma waves = highest
Radio = lowest

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16
Q

which EM wave has the highest / least wavelength?

A

radio waves = highest
gamma waves = lowest

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17
Q

where do EM waves transfer energy from and to?

A

from the source of the wave to an absorber of the wave

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18
Q

What are gamma waves used for?

A
  1. medical imaging and therapy
  2. sterilisation
  3. food preservation
  4. destroying bacteria and tumours
  5. astronomy
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19
Q

what are the risks of gamma waves?

A

are extremely penetrating and damaging to living tissues

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20
Q

X- rays

A

X- rays pass easily through the flesh but no so easily through denser materials like bones or metals.
- its the amount of radiation absorbed ( or mot absorbed) that give you an X-ray image

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21
Q

what X- rays used for? (3)

A
  1. medical and industrial imaging
  2. treating cancer
  3. detecting weapons
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22
Q

how are Gamma and X-rays used to treat cancer?

A

high doses of these rays kill all living cells - so they are carefully directed towards cancer cells, to avoid kill to many normal/ healthy cells

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23
Q

why are Gamma and X-rays harmful?

A

they are types of ionising radiation so carry enough energy to knock electrons off of atoms) –> this can cause gene mutation or cell destruction and cancer

24
Q

what are the risks of X-rays?

A

highly ionising

25
Q

UV and Fluorescence

A

Fluorescence is a property of chemicals, where UV radiation is absorbed and then visible light is emitted.
Fluorescent lights generate UV radiation, which is absorbed and re-emitted as visible light by a layer of a compound called phosphor on the inside of a bulb

26
Q

what is UV waves used for? (4)

A
  1. detect fake bank notes
  2. air purification
  3. disinfection
  4. medical and forensic photography
27
Q

what are the risks of UV?

A

too much exposure can cause skin burns, skin cancer and cataract formations in the eye

28
Q

Infrared radiation

A
  • is given out by all objects —> the hotter the object the more IR radiation it gives out

Infrared cameras can detected IR radiation, monitor temperatures and detect a range of frequencies. –> The camera detects the IR radiation and turns it into an electrical signal, which is displayed on the screen as a picture–> the hotter the object, the brighter the image is

29
Q

What are the uses of infrared radiation?

A
  1. TV controls
  2. Security –> intruder alarms detect body heat
  3. cooking food –> absorbing IR radiation causes objects to get hotter
30
Q

How do electric heaters heat up a room using IR radiation?

A

electric heaters contain a long piece of wire that heats up when a current flows through it. –> this wire then emits lots of IR radiation ( and a little visible light - the wire glows) –. The emitted IR radiation is absorbed by objects and the air in the room —> energy is transferred by the IR waves to the thermal energy stores of the objects, causing their temperatures to increase

31
Q

what are the risks of infrared radiation?

A

when emitted from high intensity sources can cause skin burns

32
Q

Micro waves

A
  • have high enough frequencies to penetrate the earth’s watery atmosphere and reach satelites.
  • Travel in straight lines through the atmosphere –> makes them good for transmitting signals
33
Q

what are the uses of micro wave radiation?

A
  1. satelite communications
  2. heating/ cooking food
34
Q

How do microwave ovens use microwaves?

A

In microwave ovens, the mircowaves are absorbed by water molecules in the food.
- The microwaves penetrate up to a few cm into the food before being absorbed and transferring the energy they are carrying to the water molecules in the food, causing the water to heat up
- The water molecules then transfer this energy to the rest of the molecules in the food by heating –> which quickly cooks the food

35
Q

How do satellite TV use microwaves?

A

For satellite TV, the signal from a transmitter is transmitted into space –> where it is picked up by the satellite receiver dish orbiting thousands of km above the earth. The satellite transmits the signal back to earth in a different direction—> where it is received by a satellite dish on the ground. There is a slight time delay between the signal being sent and received because of the long distance the signal has to travel

36
Q

what are the risks of microwave radiation?

A

humans are largely made up of water so exposure to micro waves could have a harmful effect

37
Q

Radio waves

A

Have long wavelengths so can be transmitted around earth’s surface and around buildings without interference.

38
Q

what are the uses of radio waves?

A

TV and radio communications

39
Q

what are the risks of radio waves?

A

At high intensities, radio waves cab cause internal heating of living tissues with potentially harmful effects

40
Q

what are optical fibres?

A

thin glass or plastic fibres that can carry data (e.g from a phone/ computer) over long distances as pulses of visible light

  • they work because of reflection —> the light rays are bounced back and forth until they reach the end of the fibre
41
Q

What is visible light used in? why?

A

optical fibres because it is easy to refract light enough so that it remains in narrow fibre

42
Q

what can produce radio waves?

A

Oscillations in electrical circuits can produce radio waves

43
Q

how can radio waves lead to oscillations in an electrical circuit,.

A

when radio waves are absorbed they can create an alternating current with the same frequency as the radio wave itself.
this means that radio waves can lead to oscillations in an electrical circuit

44
Q

what can result in EM waves being generated?

A

changes in atoms and the nuclei of atoms can result in EM was being generated or absorbed over a wide frequency waves

45
Q

where do gamma rays originate from?

A

they originate from changes in the nucleus of an atom

46
Q

the _____ of a wave does not change? why?

A

the frequency of a wave does not change because the source is producing the same number of oscillations (vibrations) per second

47
Q

what is wavelength directly proportional to?

A

the speed

48
Q

what 2 things of a wave changes when it travels from one medium to another?

A

speed and wavelength

49
Q

what will happens to the direction of the wave if it travels from a low density medium to a higher density medium?

A

it will refract towards the normal

50
Q

what will happens to the direction of the wave if it travels from a high density medium to a lower density medium?

A

it will refract away from the normal

51
Q

what is it called when a wave changes direction as it travels from one medium to another

A

refraction

52
Q

what type of waves are water waves

A

transverse waves

53
Q

what type of waves are sound waves?

A

longitudinal

54
Q

what is the order of the visible colours from lowest frequency to highest frequency

A

red, orange, yellow, green, blue , indigo

55
Q

which colours in the spectrum is refracted the most when it enters a glass prism?

A

violet

Physics (8 decks)

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