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Physics EoY exam revision > Waves and work power > Flashcards

Waves and work power Flashcards

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1
Q

What is a transverse wave?

A

A wave where the vibration (oscillation) is at 90° (perpendicular) to the direction of wave travel and energy transfer

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2
Q

What are some examples of transverse wave?

A

All of the EM spectrum (radio waves, microwaves, infrared radiation, visible light, ultraviolet, x-rays, gamma rays), water waves, waves when shaking a slinky from side to side, waves on a rope

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3
Q

What is a longitudinal wave?

A

A wave where the vibration (oscillation) is the same direction (parallel) to the direction of wave travel and energy transfer

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4
Q

What are some examples of longitudinal waves?

A

Sound, ultrasound

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5
Q

What are the similarities and differences between longitudinal and transverse waves?

A

Similarities: All transfer energy, All can be reflected, refracted and diffracted, all involve a vibration/oscillation

Differences: Transverse vibrate 90° to direction of travel, longitudinal vibrate in the same direction as direction of travel

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6
Q

What is a wave?

A

Something that transfer energy without a (net/overall) transfer of matter (particles)

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7
Q

What is the amplitude of a wave?

A

The maximum distance travelled by a vibration/wave from its resting position (remember to measure from middle of the wave!!)

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8
Q

What is the wavelength of a wave?

A

The distance travelled by one complete wave (peak to peak or trough to trough distance)

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9
Q

What is the frequency of a wave?

A

The number of waves per second

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10
Q

What is the time period of a wave?

A

The time then for one COMPLETE wave to pass

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11
Q

What is the unit of FREQUENCY?

A

Hertz, Hz

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12
Q

What are the similarities of electromagnetic waves?

A

They are all TRANSVERSE and travel at the SAME SPEED in a vacuum (the speed of light), they all TRANSFER ENERGY and can travel through a VACUUM

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13
Q

What are the differences between electromagnetic waves?

A

They all have different FREQUENCIES and WAVELENGTHS

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14
Q

What is the EM spectrum in order of decreasing wavelength (and increasing frequency)?

A

Radiowaves, Microwaves, Infrared radiation, Visible light, Ultraviolet, X-rays, Gamma rays (learn song!!)

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15
Q

What are the colours of visible light in order of decreasing wavelength (and increasing frequency)?

A

Red, Orange, Yellow, Green, Brown, Indigo, Violet (ROYGBIV)

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16
Q

What are the uses of the different parts of the EM spectrum?

A

Radio waves: Broadcasting and communications

Microwaves: Cooking and satellite transmissions

Infrared: heaters and night vision equipment

Visible light: optical fibres and photography

Ultraviolet: fluorescent lamps used to detect forged bank notes, sterilising drinking water

X-rays: Observing the internal structures of objects and materials and medical applications

Gamma rays: Sterilising food and medical equipment, killing cancer cells, detecting cancer cells

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17
Q

How do microwaves cook your food?

A

The microwaves make the water molecules in food vibrate, causing them to heat up

18
Q

How does UV light detect forged bank notes?

A

The UV light is absorbed by special ink on the notes and then re-emitted (released) as visible light so you can see it. This is called FLUORESCING.

19
Q

How do Gamma rays, X rays and UV cause cancer and kill cells

A

They are IONISING and makes parts of the cell chemically reactive that shouldn’t be. So unexpected chemical reactions happen, usually killing the cell but sometimes causing mutations in your DNA that led to cancer.

20
Q

What are the dangers of microwaves, infrared radiation, UV and gamma rays? How would you protect yourself?

A

MICROWAVES: internal heating of body tissue (internal burns) Put the microwaves in protective cases so they do not pass through you, close microwave door.

INFRARED: skin burns. Wear protective clothing, do not expose yourself for too long.

ULTRAVIOLET: damage to surface cells and blindness (skin cancer) Wear protective clothing/sun cream and UV protective sunglasses.

GAMMA RAYS/X-RAYS: cancer, mutation. Put gamma rays in lead casing so they cannot get out. Do not expose yourself for a long time, try to work from a different room. Monitor exposure using a film badge

21
Q

What two things can happen to a wave when it encounters a new material?

A

Reflected or refracted

22
Q

What is the Law of Reflection

A

Angle of incidence = Angle of reflection

23
Q

What is the normal line?

A

An imaginary line that is drawn at 90° to the surface where the ray hits it.

24
Q

Where are the angles of incidence and reflection measured from?

A

The angles are always measured between the normal line and ray

25
Q

What is a real image?

A

An image that can be projected onto a screen e.g. a projector, camera etc because the rays converge (cross over)

26
Q

What is a virtual image?

A

An image that cannot be projected onto a screen (because it’s on the same side of the lens/mirror as the object causing it – the object looks like it’s somewhere it isn’t) e.g. mirror images, magnifying glass image. The rays never actually converge (cross over)

27
Q

Wave equation

A

wave speed = Wavelength x Frequency

28
Q

How to work out frequency of the waves

A

1/Time period

29
Q

Too much exposure to infrared and ultraviolet can cause damage to the human body. What damage can cause?

A

Infrared can cause skin burn, ultraviolet can cause damage to surface cells, skin cancer, sun burns

30
Q

Which colour has longest wavelength?

A

Red

31
Q

Where is gravitational potential energy in?

A

Weights, book on shelf, kite in the sky, a in orbit in earth

32
Q

Where is kinetic energy in?

A

Moving car, spinning top, person running, a ball being thrown

33
Q

Where is sound energy in?

A

Sound by musical instruments, human voices as well

34
Q

What force is used by the weightlifter to hold the weight still if he lifted a 2250 newton weight above his head?

A

2250 newtons because force must be balanced and force are equal and opposite

35
Q

What is the word equation for power?

A

Power = Work done/Time Taken

36
Q

What is the units for work done?

A

Joules

37
Q

Formula for work done

A

Work done = Force x Distance

38
Q

Why does a ball fall to the ground when you drop it?

A

This happens because the Earth pulls the ball towards it with a force called gravity. Forces are measured in units called newtons.

39
Q

What is the formula for force?

A

Force = Mass x Acceleration

40
Q

What is the formula for gravitational potential energy?

A

GPE= Weight x Height

Physics EoY exam revision (3 decks)

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