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Physics - Waves > No Longer On Exam > Flashcards

No Longer On Exam Flashcards

1
Q

What type of spectrum do EM waves form?

A

A continuous spectrum.

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2
Q

Order the types of EM waves/radiation from lowest to highest frequency

A
  • Radio waves.
  • Microwaves.
  • Infrared.
  • Visible light.
  • Ultraviolet.
  • X-rays.
  • Gamma rays.
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3
Q

How do the speeds to EM waves/radiation differ in a vacuum and in air?

A

Electromagnetic waves all travel at the same speed in a vacuum and in the air.

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4
Q

What property of waves in different mediums causes refraction?

A
  • Velocity.

- Wave speed is slower in denser materials, causing refraction.

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5
Q

In which direction do waves refract when entering a denser medium?

A
  • When entering a more dense medium, the wave slows down.
  • This causes them to bend towards the normal.
  • This lead to the angle of refraction being less than the angle of incidence.
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6
Q

What type of waves can be produced by oscillations in an electrical circuit?

A

Radio waves.

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7
Q

How can radio waves create an alternating current in a circuit?

A

When radio waves are absorbed, they can create oscillations in a circuit with same frequency as the radio waves creating AC.

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8
Q

Where do gamma rays originate from?

A

They originate from changes in the nuclei of atoms.

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9
Q

What health effects can ultraviolet waves cause?

A
  • They can cause the skin to age prematurely.

- Increase risk of developing skin cancer.

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10
Q

What health effects can X-rays and gamma rays cause?

A
  • They are ionising radiation so can cause mutations in genes.
  • They can lead to increased risk of developing various cancers.
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11
Q

Give 3 practical uses for infrared radiation

A
  • Electrical heaters.
  • Cooking food.
  • Infrared cameras.
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12
Q

How can infrared be used for cooking food?

A

Infrared light has frequencies which are absorbed by some chemical bonds. The internal energy of the bonds increases when they absorb infrared light, which causes heating.

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13
Q

Give 2 practical uses for microwave radiation

A
  • Satellite communications.

- Cooking food.

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14
Q

How can microwaves be used for cooking food?

A

High frequency microwaves have frequencies which are easily absorbed by molecules in food. The internal energy of the molecules increases when they absorb microwaves, which causes heating.

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15
Q

How can microwaves be used for satellite communications?

A

Microwaves pass easily through the atmosphere, so they can pass between stations on earth and satellites in orbit.

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16
Q

Give 2 practical uses for radio waves

A
  • Television transmission.

- Radio transmission.

17
Q

Give a practical use for visible light

A

Fibre optic communications.

18
Q

What wave phenomenon is used by lenses to form an image?

A

Refraction.

19
Q

How does a convex lens form an image?

A

Parallel rays of light are refracted and brought together at a point known as the principal focus.

20
Q

What is meant by the focal length of a lens?

A

The distance from the lens to the principal focus.

21
Q

What is the difference between the image produced by a convex and a concave lens?

A
  • Convex lenses can produce real or virtual images.

- Concave lenses can only produce virtual images.

22
Q

Why does magnification not have a unit?

A
  • It is the ratio between image height and object height.

- Ratios do not require units.

23
Q

What symbol is used to represent a convex lens in a ray diagram?

A

↕

24
Q

What symbol is used to represent a concave lens in a ray diagram?

A

Similar to the convex, but arrows point towards the line.

25
Q

What determines the colour of visible light waves?

A

The wavelength and frequency of the light waves.

26
Q

What colour of visible light has the highest frequency?

A

Blue.

27
Q

What colour of visible light has the largest wavelength?

A

Red.

28
Q

What is meant by the term ‘specular reflection’?

A

Reflection from a smooth surface in a single direction.

29
Q

What is meant by the term ‘diffuse reflection’?

A

Reflection from a rough surface which causes scattering.

30
Q

How does a red colour filter work?

A
  • A red filter absorbs all wavelengths of light other than those in the red range of the spectrum.
  • This means only red light is transmitted through the filter.
31
Q

What determines the colour of an opaque object?

A
  • Different objects reflect different wavelengths of lights by different amounts.
  • The wavelengths that are most strongly reflected determine the colour.
32
Q

What happens to the wavelengths of light that aren’t reflected by an opaque object?

A

Any wavelengths that aren’t reflected are absorbed by the object.

33
Q

What colour does an object appear if all wavelengths are reflected by equal amounts?

A

White.

34
Q

What colour does an object appear if all wavelengths are absorbed?

A

Black.

Physics - Waves (3 decks)

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