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Physics > Waves, EM spectrum, black+silver cans > Flashcards

Waves, EM spectrum, black+silver cans Flashcards

1
Q

What travels in transverse waves?

A

Light

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2
Q

What travels in longitudinal waves?

A

sound

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3
Q

Give the definition of Amplitude

A

The maximum displacement of a point from the equalibrium

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4
Q

Give the definition of frequency

A

The amount of waves passing in a second

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5
Q

How do you work out frequency?

A

Frequency = 1/Time period

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6
Q

Time period

A

The length of time taken for a wave to pass fully

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7
Q

How do you work out TIme period?

A

Time period = 1/Frequency

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8
Q

What is the equation which links velocity, frequency and wavelength?

A

Wavespeed or V (m/s) = Frequency (Hz) x Time period (s)

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9
Q

What is the order of prefixes from high to low

A

Terra, GIga, Mega, Kilo, Centi, Milli, micro, nano

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10
Q

How do oscillations move in a:
Transverse Wave
Longitudinal wave

A

Perpendicular
Parallel

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11
Q

What does a high frequency mean?

A

Short wavelength

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12
Q

What does a low frequency mean

A

Long wavelength

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13
Q

Do low frequency waves have a lower or higher energy than high frequency waves

A

LOWER
the higher the frequency is, the more energy a wave has
FOr example, Gamma rays

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14
Q

What can longitudinal waves do, but transverse cannot?

A

Travel through a liquid

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15
Q

What can transverse waves do, but longitudinal waves cannot

A

Travel through a vaccum

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16
Q

RP: Measuring water ripples
How do you measure the wavelength?

A

Place a ruler next to the ripples and take a photo. Use the image to determine the distance for one wave.

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17
Q

RP: Measuring water ripples
How do you measure frequency?

A

Take a video recording of the ripples. Count how many waves pass per second or reach a fixed point.

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18
Q

RP: Measuring water ripples
What are the control variables?

A

Same water depth

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19
Q

RP: Measuring water ripples
How would we calculate the wavespeed?

A

By multiplying the wavelength and frequency

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20
Q

Sound waves

A

Travel in longitudinal waves
Light travels faster than sound

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21
Q

What does:
1) A high frequency create
2) A low frequency create in terms of sound

A

1) A high pitched sound
2) A low pitch sound

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22
Q

What is relfection?

A

Reflection is when a wave ‘bounces’ off a surface

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23
Q

What is the angle of incidence the same as?

A

The angle of incidence the same as the angle of reflection. However the angle of refraction is different

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24
Q

What is refraction?

A

Refraction is the bend of a wave when it changes speed.

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25
Q

Name the waves in the electromagnetic spectrum - from lowest frequency to highest

A

Radio, microwaves, Infrared, VIsible light, Ultraviolet, X-rays and gamma rays

26
Q

What speed to all the electromagnetic waves travel at

A

300,000,000 m/s (3x10 to the power of 8)

27
Q

Radio waves
1) sources + uses
2) Dangers

A

1) Communication, television, moblie phones, satellites
2) No danger

28
Q

Microwaves
1) sources + uses
2) Dangers

A

1) Heating food, bluetooth, satellites, speed cameras
2) Heating of tissues which can cause burns

29
Q

Infrared
1) sources + uses
2) Dangers

A

1) Thermal imaging, TV-remote and electric heaters
2) Skin burns

30
Q

Visible light
1) sources + uses
2) Dangers

A

1) Enables us to see things, used for torches and lamps
2) Can damage your retina and cause blindness

31
Q

Ultraviolet
1) sources + uses
2) Dangers

A

1) To sterilise things, curing your nails, tanning beds
2) Can cause skin cancer

32
Q

X-rays
1) sources + uses
2) Dangers

A

1) Medical imaging at hospitals
2) Can cause cancer and cell mutation

33
Q

Gamma Rays
1) sources + uses
2) Dangers

A

1) Cancer treatment, sterilisation
2) Can cause cancer and cell mutation

34
Q

what happens if light passes through the centre of a lens, or somewhere else

A

centre of lense - doesn’t change direction
other: light bends in different directions

35
Q

what do concave lenses produce

A

virtual images

36
Q

what do convex lenses produce

A

virtual or real images

37
Q

whats a virtual image

A

image is on the same side of lense as the object

38
Q

describe the differences between longitudinal waves and transverse waves

A

direction of energy transfer is parallel to oscillations in transverse waves, direction of energy transfer is perpendicular to oscillations in longitudinal waves
transverse waves’ pressure is constant. pressure in longitudinal waves is not constant - changes

39
Q

describe a method to measure speed of waves on a string

A

1) attach string to a vibration generator and add a 200g hanging mass and pulley to pull string taut. Place a wooden bridge under string near pulley.
2) turn vibration generator on until you can see stationary waves
3) measure a few eg, 5 half wavelengths and calculate a mean.
4) then double half wavelength to give full wavelength
5) frequency is frequency of power supply
6) use wave speed = frequency x wavelength

40
Q

describe the differences between longitudinal and transverse waves

A

Longitudinal: oscillation is parallel to the direction of energy transfered. Can travel through liquid
Transverse: oscillation is perpendicular to the direction of energy transfered. Can’t travel through liquid

41
Q

whats the wave speed

A

the speed at which energy is transferred through the medium

42
Q

equation linking wavespeed frequency and wavelength

A

wave speed = frequency x wavelength

43
Q

what is frequency measured in

A

hertz -> Hz

44
Q

describe a method to measure the speed of sound waves in the air

A

1) Gather two microphones, a fast timer, a hammer, a block of metal and a metre ruler
2) place two microphones a meter apart, attached to a fast timer
3) Bang the hammer against the block of metal so it makes a sound
4) the fast timer will record the time the waves take to travel. record the time on the fast timer onto a table
5) repeat 5 times and calculate a mean time
6) use speed of waves = distance divided by mean time

45
Q

describe a method to measure speed of waves through a solid

A

1) Attach a string toa vibration generator and use a 200g hanging mass and pulley to pull the string taut. Place a wooden bridge under the string near the pulley.
2) Switch on the vibration generator and adjust the wooden bridge until stationary waves can be clearly seen
3)Measure half a mean half wave length and double it to get a full wavelength
4)The frequency is the frequency of the power supply.
Calculate the speed of the waves using: wave speed = frequency × wavelength.

46
Q

how do we hear sound

A

sound waves cause the ear drum and other parts of our ears to vibrate which causes the sensation of sound.

47
Q

range of normal human hearing

A

20 HZ to 20 kHz

48
Q

uses of ultrasound

A

medical imaging - reflection
catarct procedures - vibration
breaking up gallstones - vibration
industrial imaging - reflection

49
Q

describe an experiment to show the angle of incidence and refraction in a light ray

A

1) place a glass block on a piece of paper and draw around it with a pencil
2) measure 9 angles of incidence: 10, 20, 30, 40, 50, 60, 70, 80, 90 degrees
3) shine a light ray with a raybox through the glass block at an angle of 10 degrees of incidence. mark where the refracted light ray is
4) repeat step 3 but with the different angles of incidence: 20, 30, 40, 50, 60 , 70, 80, 90 and mark on the refracted rays
5) remove the glass block and measure the angles of refraction of the refracted rays from the normal line
6) record on a table and compare results - > angle of incidence and refraction should be different and not equal

50
Q

what are P waves and S waves

A

P waves are longitudinal seismic waves
S waves or transverse seismic waves

51
Q

how does a microwave heat food

A

Microwaves are easily absorbed by water molecules in food, causing them to vibrate more vigorously. The microwave energy is changed to heat energy as it is absorbed, which cooks the food.

52
Q

how is ultrasound used to deteic a foetus

A
  • pulse of ultrasound directed towards the foetus
  • when they reach the boundary between the fluid of the womb and the skin of the foetus they are partially reflected
    -The reflections are deflected and their timings and distributions are used to produce a video image
53
Q

how are radiowaves created

A

Radio waves can be produced by
oscillations
in electrical circuits. When radio waves are absorbed by a
conductor
, they create an
alternating current
. This electric current has the same frequency as the radio waves. Information is coded into the wave before transmission, which can then be decoded when the wave is received. Television and radio systems use this principle to broadcast information.

54
Q

objects that transmirt light are what

A

transparent or transulcent

55
Q

the hotter the body the..

A

the hotter the body, the more radiation it emits/radiates in a given time

56
Q

image produced by concave is always what

A

virtual

57
Q

image produced by convex is always what

A

virtual or real
virtual is if the image appears on the same side as object

58
Q

difference between concave lense and a convex lense

A

concave has thinner centre and wider edges. convex has thicker centre and thinner outer edges
light in convex lense converges, light in concave lense diverges

59
Q

factors which determine temperature of the earth

A

concentration of greenhouse gases such as water vapour, methane and carbon dioxide.
axis and tilt of the earth
distance of earth from sun.

60
Q

The inside and outside surfaces of the oven are light-coloured and shiny. Explain why.

A

Infra-red radiatio is reflected by shiny surfaces. The radiation given off from the heating elements would therefore be reflected back from the inside of the oven towards the bicuits, increasing the efficiency of the oven.The outside surface being shiny reduces the loss of energy from the oven, as shiny surfaces are poor emitters of radiation.

Physics (7 decks)

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