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gcse physics year 11 > topic 6 continued > Flashcards

topic 6 continued Flashcards

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1
Q

how do EM waves transfer energy

A

they transfer energy from the source of the waves to an absorber

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2
Q

how do microwaves transfer energy

A

from the source which is the microwave to the absorber which is the food

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3
Q

the frequency … from radio waves to the gamma rays

A

increases

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4
Q

the wavelength … from radio waves to the gamma rays

A

decreases

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5
Q

what can EM waves travel through

A

a vacuum (space)

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6
Q

all EM waves travel at the same … in a vacuum

A

speed

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7
Q

at what speed do EM waves travel in a vacuum

A

3 x 10^ 8 m/s

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8
Q

what happens when EM waves are generated or absorbed

A

changes takes place in atoms or in the nuclei of atoms

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9
Q

how can an em wave be generated

A

by a change to the nucleus

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10
Q

how can radio waves be produced

A

when electrons oscillate (move backwards and towards)in electric circuits

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11
Q

give an example of how radio waves can be absorbed

A

by an electrical circuit in an aerial- this causes the electrons in the circuit to oscillate

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12
Q

what type of current can radio waves create and what does it have the same of

A

alternating current with the same frequency as the radio waves

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13
Q

why are radio waves used in TVs and radios

A

because they can travel long distances before being absorbed e.g. by buildings and trees

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14
Q

what can radio waves do in the atmosphere

A

they can reflect off a layer of charged particles in the atmosphere- this allows us to send radio waves at very long distances around the earth

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15
Q

why are microwaves used in communication with satellites

A

because microwaves can pass through the earths atmosphere without being reflected or refracted

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16
Q

why is infra-red used to heat objects etc

A

because the energy of the infra-red is easily absorbed by the surface of the objects

17
Q

What can EM waves do that leads to refraction

A

They travel at different speeds in different materials

18
Q

EM waves vary in wavelength from …

A

10^-5 - 10^4

19
Q

Wavelength of radiowaves

A

1m - 10^4

20
Q

Microwaves wavelength

A

10^-2m

21
Q

Infra-red wavelength

A

10^-

22
Q

Visible light wavelength

A

10^-7m

23
Q

Ultraviolet wavelength

A

10^-*8m

24
Q

X-rays wavelength

A

10-10 m

25
Q

Gamma rays wavelength

A

10^-15m

26
Q

Why is there a large range of frequencies in the EM spectrum

A

Because the EM waves are generated by a variety of changes in atoms and their nuclei

27
Q

Changes in the nucleus of an atom creates …

A

Gamma rays

28
Q

What bit of the spectrum can our eyes detect

A

Visible loght

29
Q

What does it mean is a wave is ABSORBED by the second material

A

The wave transfers energy to the materials energy stores. Often the energy is transferred to a thermal energy store which leads to HEATING

30
Q

What does it mean if the wave is TRANSMITTED through the second material

A

The wave carries on travelling through the new material which often leads to refraction

31
Q

What does it mean if the wave is REFLECTED

A

This is where the incoming ray is neither ABSORBED or TRANSMITTED but instead is sent back away from the second material

32
Q

If the wave hits the boundary at an angle it …

A

Changes direction- it is refracted

33
Q

How much a wavs is refracted depends on what

A

How much the wave speeds up or slows down which depends on the density of the 2 materials

34
Q

When will a wave speed up

A
  • when its travelling along the normal

- when the wave bends AWAY from the normal

35
Q

When will a wave slow down

A

-if the wave BENDS towards the normal

36
Q

How can long wavelength radio-waves travel at long distances

A

Because long wavelengths diffract around the curve surface of the earth

37
Q

How can short wavelength radio signals be received at long distances by a TRANSMITTER

A

Because they are reflected from the ionosphere- an electrically charged layer in the earths upper atmosphere

38
Q

What is fluorescence a property of

A

Certain chemicals where ultra-violet radiation is absorbed and then visible light is emitted

39
Q

What is period

A

The total time taken for a full cycle of the wave

gcse physics year 11 (8 decks)

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