P12 Flashcards

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1
Q

What type of lens is thicker in the middle than at the edges?

A

Convex lenses

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2
Q

Which type of lens causes light rays to diverge?

A

Concave

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3
Q

Which type of lens is used in a camera?

A

convex

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4
Q

What is a real image?

A

A real image is an image that can be projected onto a screen

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5
Q

What is a virtual image?

A

An image from which rays of light appear to come but do not do so in reality

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6
Q

What types of images do concave lenses form?

A

Only virtual images

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7
Q

What name is given to a material that absorbs some wavelengths of visible light and transmits others?

A

A filter

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8
Q

Why can we see through glass?

A

Almost all light waves are transmitted through glass, making it a transparent object

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9
Q

What name is given to the distance between the lens and the principal focus?

A

Focal length

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10
Q

What is an area of low pressure in a wave called?

A

A rarefraction

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11
Q

What is denser (air, glass or water)?

A

Glass

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12
Q

What happens to a light ray when it travels from water into air?

A

It bends away from the normal because it passes into a less dense material and speeds up

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13
Q

What are the units for magnification?

A

Magnification has no units since it is a ratio of 2 quantities with the same units.

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14
Q

What state of matter does sound travel the fastest?

A

Solids, because the particles are more tightly packed

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15
Q

Waves transfer ____

A

energy from place to place, without transferring any matter

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16
Q

What is the amplitude?

A

The amplitude of a wave is the distance from the centre line (or the still position) to the top of a crest. or to the bottom of a trough.

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17
Q

What is frequency?

A

Frequency is the number of complete waves passing a certain point per second measured in Hz. 1 Hz is equal to 1 wave per second.

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18
Q

What is wavelength?

A

The wavelength of a wave is the distance between a point on one wave and the same point on the next wave.

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19
Q

What are transverse waves?

A

Transverse waves are waves whose oscillations are at right angles to the direction of travel and energy transfer.

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20
Q

What are longitudinal waves?

A

In longitudinal waves, the oscillations are along the same direction as the direction of travel and energy transfer. (parallel)

21
Q

Examples of transverse waves

A

All EM waves and ripples on water

22
Q

Examples of longitudinal waves

A

Sound waves, seismic waves, P- waves

23
Q

What is the frequency range of human hearing?

A

20Hz - 20KHz

24
Q

What is reflection?

A

Reflection involves a change in direction of waves when they bounce off a barrier.

25
Q

What is refraction?

A

Refraction is the process by which a wave changes speed and sometimes direction upon entering a denser or less dense medium.

26
Q

What is the angle of incidence?

A

The angle of incidence is the angle between the incoming wave and the normal.

27
Q

What is the angle of reflection?

A

The angle of reflection is the angle between the reflected wave and the normal.

28
Q

Angle of Incidence is greater/equal/less than the Angle of Reflection

A

Angle of Incidence = Angle of Reflection

29
Q

What is the law of reflection?

A

The law of reflection states that, on reflection from a smooth surface, the angle of the reflected ray is equal to the angle of the incident ray.

30
Q

What is specular reflection?

A

Specular reflection happens when a wave is reflected in a single direction by a smooth surface E.g when light is reflected by a mirror you get a nice clear reflection

31
Q

What is diffuse reflection?

A

Reflection from a rough surface is called diffuse reflection because the reflected rays are scattered in lots of different directions

32
Q

high to low Electromagnetic Spectrum?

A

radio - microwave - infared - visible light - ultraviolet - x-rays - gamma rays

33
Q

what is radio waves used?

A

used to broadcast radio and television

34
Q

what is microwaves used for?

A

cooking,radar,telephone and other signals

35
Q

what is infared used for?

A

transmits heat from sun, fires radiators

36
Q

what is visible light used for?

A

makes things to be seen

37
Q

what is uv used for?

A

absorbed by skin

38
Q

what is rays used for?

A

used to view inside bodies and objects

39
Q

what is gamma rays used for?

A

used in medicine for killing cancer cells

40
Q

3 things all electromagnetic waves have in common

A
  • transfers radiation as energy from waves
  • can travel through a vacum
  • travel at same speed
41
Q

What is the speed of light in a vacuum or air?

A

300,000,000 m/s

42
Q

Which colour is the best absorber of radiation?

A

Black

43
Q

What gases in the atmosphere change the balance of infrared radiation absorbed and emitted by the Earth?

A

Greenhouse gases change the balance of infrared radiation absorbed and emitted by the Earth.

44
Q

What health effects can ultraviolet waves cause?

A

Cause the skin to age prematurely and increase risk of developing skin cancer

45
Q

Uses of radio waves

A

Radio waves are used for communication such as broadcasting television and radio, communications and satellite transmissions.

46
Q

What is echo?

A

A reflection of sound waves from a smooth surface

47
Q

Uses of infrared

A
  • security systems
  • thermal imaging
  • electrical heaters
48
Q

Define ultrasound

A

Ultrasound is sound with a frequency greater than 20,000 Hz