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Science Year 8 > Waves > Flashcards

Waves Flashcards

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1
Q

What’s an oscillation?

A

When the particle in a wave moves backwards and forwards or up and down yet returns to the starting position however the wave itself moves forwards

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2
Q

What are the two types of wave and give some examples of each

A

Longitudinal- sound,seismic P waves and pressure waves
Transverse - light, sea waves,seismic S waves and Mexican waves

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3
Q

What are transverse waves?

A

The wave oscillates perpendicularly the direction of the motion

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4
Q

What angle do each part of the wave move at in a transverse wave?

A

90 degrees to the direction the energy is moving in

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5
Q

Describe a longitudinal wave

A

The wave moves in the same direction as the direction the energy is going, they move in a plane parallel to the direction of the wave

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6
Q

What is a pressure wave?

A

When you speak to somebody and the air vibrates in longitudinal waves

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7
Q

What is amplitude?

A

The maximum displacement of a wave from its rest position measured in metres (linked with volume)

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8
Q

What is wavelength?

A

The distance between two peaks and two crests measured in meters

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9
Q

What is frequency?

A

The number of oscillations/vibrations per second (linked with pitch)

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10
Q

What unit is frequency measured in?

A

Hertz (hz)

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11
Q

If a wave can travel through a substance the wave is what?

A

Transmitted through it

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12
Q

What does opaque, transparent and translucent mean?

A

Opaque - completely not see through
Translucent - partly see through
Transparent- completely see through

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13
Q

In a vacuum what speed does EM waves travel at?

A

The speed of light (they are transverse waves)

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14
Q

The higher the frequency the higher the e…

A

Energy of the wave

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15
Q

What is the only difference between electro magnetic waves?

A

Frequency and wave length

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16
Q

What is the spectrum?

A

Each colour corresponds to a different wave length

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17
Q

Where are violet and red on the spectrum?

A

Red - the longest - refracted the least in a prism
Violet - the shortest - refracted the most in a prism

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18
Q

What are the primary and the secondary colours of light?

A

Primary colours - Red, green , blue
Secondary colours - magenta, cyan and yellow

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19
Q

What do filters do?

A

They absorb all colours and don’t posses and transmit those that do

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20
Q

What do surfaces do?

A

They absorb all colours and do not posses and reflect those that do

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21
Q

What do surfaces do?

A

They absorb all colours and do not posses and reflect those that do

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22
Q

WHen do objects emit radiation?

A

Due to their temperature - the higher the temperature the greater the amount of infrared emmited

23
Q

When can an object emit visible light?

A

When it gets hot enough

24
Q

What does infrared cause!?

A

Causes heat - exposure to small a,lungs warms a person (e.g sunlight)

25
Q

What does large amount exposure to infrared radiation cause?

A

Burns

26
Q

What does ultraviolet light cause?

A
  • tanning UV
  • materials to fluorescence (shine with visible light)
27
Q

What could ultraviolet light be used for?

A

To detect forgeries on bank notes

28
Q

What are the three main categories of ultra violet radiation and their properties

A
  • UVA - longest wave length, tanning, 99% UV light to reach the earth
  • UV B - medium wave length, damages cells, causes sunburn and skin cancer
  • UV C - shortest wave length, the most damaging, filtered out by earths ozone layer
29
Q

What type of waves can be reflected?

A

All

30
Q

What’s the normal?

A

An imaginary line drawn at 90 degrees to the mirror

31
Q

What’s an incident ray?

A

When the ray hits the mirror and goes IN the mirror

32
Q

What’s a reflected ray?

A

When the ray leaves the mirror

33
Q

How do you measure the angle of incidence?

A

Between the normal and the incidence ray

34
Q

How do you measure the angle of reflection?
.

A

It’s measured between the Normal and the reflected ray

35
Q

What’s the law of reflection?

A

The angle of incidence = the angle of reflection

36
Q

When do sound and light waves change speed?

A

When they pass between the boundaries of two different substances with different density’s

37
Q

What is refraction the change of?

A

Direction

38
Q

At what speed will the light move through a more dense substance?

A

Slower speed

39
Q

What’s superposition?

A

When waves meet with each other they create an interference pattern

40
Q

High frequency’s =…

A

High pitch

41
Q

What is the human hearing range?

A

Between 20 Hz - 20,000

42
Q

What does the amplitude tell us?

A

The volume - its an indicator of how much energy is transferred

43
Q

What’s volume measured in?

A

Decibels (dB)

44
Q

Hard surfaces _______ , soft __________ it

A

Reflect sound, absorb

45
Q

Flat surfaces ________ , rough _________ it

A

Reflects sound, scatters

46
Q

What does the electrical current cause the solenoid to become?

A

Magnetised

47
Q

Since the solenoid is in a magnetic field what happens?

A

The solenoid experiences a force

48
Q

What causes the magnetic force to either move the solenoid out or into the permanent magnet, due to the change in direction of the force?

A

Alternating current

49
Q

What does the diaphragm in a speaker do?

A

Moves the solenoid which causes air molecules near the diaphragm to vibrate

50
Q

What causes the flexible membrane to vibrate back and forth?

A

The sound wave

51
Q

How is the small electrical current in microphones caused?

A

The solenoid is moved forwards and backwards through the magnetic field

52
Q

Why does the direction of the electrical current change?

A

The vibration of the solenoid changing direction

53
Q

Since the signal is weak what needs to be happened in microphones to be used in a loudspeaker?

A

It needs to be amplified

Science Year 8 (7 decks)

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