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Physics Theory > Ch15 The Electromagnetic Spectrum > Flashcards

Ch15 The Electromagnetic Spectrum Flashcards

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1
Q

Define ultraviolet radiation:

A

Electromagnetic radiation with a shorter wavelength than visible light

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2
Q

Define ultraviolet radiation:

A

Electromagnetic radiation with a shorter wavelength than visible light

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3
Q

Define electromagnetic spectrum:

A

The family of radiations similar to light

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4
Q

Define analogue signal:

A

A signal which varies continuously in frequency and amplitude

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5
Q

Define digital signal:

A

A signal that consists of a series of pulses neither on/of

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6
Q

How is an electromagnetic spectrum formed?

A

When light passes through a prism and some colors are refracted more than others

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7
Q

What end of the spectrum is refracted the most?

A

Violet end

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8
Q

What causes different colors light waves?

A

Different frequencies

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9
Q

What physicist described light as small oscillations in electric and magnetic fields which he called electromagnetic waves?

A

Scottish physicist, James Clerk Maxwell

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10
Q

What causes light waves to have different effects on different objects?

A

The different frequencies of light

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11
Q

What is the speed of light in a vacuum?

A

3 x 10^8 m/s

(Approx. the same speed in air)

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12
Q

What has a greater wavelength?
Red light or violet light?

A

Red light has a greater wavelength

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13
Q

What has a bigger frequency?
Red light or violet light

A

Violet light

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14
Q

What is the frequency of visible light?

A

10^14 Hz

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15
Q

What is the wavelength of red light?

A

700nm (nanometers)

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16
Q

What is the wavelength for violet light?

A

400nm

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17
Q

Change 400nm to meters

A

400 /1 000 000 000 m

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18
Q

List the names of the waves in the electromagnetic spectrum in order of increasing wavelength:

A

1) Gamma rays
2) X-rays
3) Ultraviolet
4) Visible light
5) Infrared
6) Microwaves
7) Radiowaves

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19
Q

List the names of the waves in the electromagnetic spectrum in order of increasing frequency:

A

1) Radio waves
2) Microwaves
3) Infrared
4) Visible light
5) Ultraviolet
6) X-rays
7) Gamma rays

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20
Q

Name 2 uses of radio waves:

A

1) broadcast radio/television
2) RFID chips with medical information/passport/contactless bank card

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21
Q

What does RFID stand for?

A

Radio frequency identification

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22
Q

Give 2 uses for microwaves:

A

1) Satellite television broadcasting
2) Transmit mobile phone signals between masts
3) microwaves ovens emit microwaves which are absorbed by molecules in food causing heat

23
Q

Give uses for 5 uses for infrared radiation:

A

1) remote controls for devices (such as tv remote)
2) grills and toasters use IF radiation to cook food
3) also used together with optical fibers
4) can be used in medicine to detect heat which may indicate infection
5) can be used in medicine to speed up healing and reduce pain

24
Q

Give 2 uses for visible light:

A

1) photosynthesis
2) provides us with vital information about the world through our eyes, cameras, telescopes

25
Q

Give 3 uses for ultraviolet light:

A

*Causes some chemicals (sweat, saliva) to emit visible light.

1) forensic scientists use this to find evidence at crime scenes invisible to the human eye
2) chemicals that glow under UV can be used for security marking such as bank notes /valuable equipment
3) sterilize water (UV kills DNA in bacteria/viruses contained in water which makes them useless)

26
Q

Give uses for X-rays:

A

*Can penetrate solid material

1) used in security scanners in airports
2) used in hospitals and clinics to see inside patients without the need for surgery

27
Q

How do x-rays work?

A

Some material absorbs x-rays more than other causing them to create a darker shadow on the scan

28
Q

Give uses for gamma rays:

A

1) damage/kill living cells
Targeted beam of gamma rays can be used to kill cancerous cells
3) sterilize surgical instruments by killing bacteria
4) can detect cancer

29
Q

Why can infrared radiation be hazardous?

A

Can burn you

30
Q

Why can UV radiation be hazardous?

A

Can damage skin cells which may leas to skin cancer

Can damage eye cells - wear sunglasses/ hat in bright light

31
Q

True/false: The heigher the frequency of the wave, the greater harm it can cause

A

True

32
Q

What 2 rays are the most dangerous part of the electromagnetic spectrum and why?

A

1) X-rays
2) Gamma rays

Can cause cell mutations that might lead to cancer

33
Q

How can workers protect themselves from the dangerous radiation when working with gamma/X-rays?

A

1) Stand well away when a patient is being examined
2) Enclose the equipment in a metal case to absorb the rays

34
Q

Compare geostationary satellites and low earth orbit satellites?

A

Geo
1) Orbit at the same rate as what earth turns so they stay above one point of the earths surface

2) 35 000km above the earths surface and above the equator

3) Waves travel a long way to satellite - delay in conversation

4) covers a large area

5) transmits data fast - suitable for satellite tv and some phones

Low earth
1) Orbit earth in *2 hours *

2) 2000km above earths surface

3) Waves don’t have travel that far - no delay in conversation

4) more needed as they only cover a small area of earths surface

5) does not transmit data fast - not suitable for tv transmissions

35
Q

Why are microwaves most suitable for mobile phones and wireless internet?

A

1) can pass through most walls
2) only need a small aerial

36
Q

What radiation is used for Bluetooth?

A

Radio waves
*connection is weakened as passes through walls
*short range signal is useful for communication between electronic devices such as in hands-free mobile phone systems

37
Q

What radiation does optical fibers use and why?

A

Infrared radiation
Visible light

*Optical fibers are made of glass and transparent to IR and visible light
*These waves have higher frequency and carry more data
*This is vital for high speed broadband connections

38
Q

Give an example of an analogue signal:

A

Sound wave

39
Q

Compare analogue and digital signal:

A

Analogue
1) electrical signal transmitted through copper wires

2) transmission process for analogue signals cause wave to become distorted and unwanted vibrations are heard as noise

3) slower since sound wave is converted to electrical signal and then back to sound wave

4) varies continuously

Digital
1) electrical signal transmitted through optical fibers

2) clearer

3) faster and carry more data

4) either on/off

40
Q

Describe what happens with radiation during making a digital phone call:

A

1) analogue sound wave from caller is encoded by converter

2) converter turns sound wave into series of pulses

3) digital signal is carried along optical fibers by visible pulses/infrared waves

4) signal passes through 1/more regenerators that clean up signal removing any distortion

5) regenerators boost the signal if it has lost power

6) second converter switches the signal back to an analogue signal which can be converted back to sound wave

41
Q

Why is visible light referred to as electromagnetic radiation?

A

It is because there are electric and magnetic fields that make up the radiation

42
Q

Are electromagnetic waves, transverse, or longitudinal?

A

Transverse

43
Q

What are the two components of an electromagnetic wave?

A

Electric field oscillating in one plane produces a magnetic field oscillating in a plane at right angles to it, oscillating at the same frequency

44
Q

What causes the electromagnetic wave to propagate forward?

A

When two oscillating electric and magnetic fields regenerate each other (mutually regenerating) It causes the wave to propagate forward.

45
Q

What does the symbol c stand for?

A

Speed of electromagnetic wave through space
3 x 10^8 m.s^-1

46
Q

What’s a logarithmic scale?

A

A method for graphing and analyzing a broad range of values in a compact form

47
Q

Frequency and wavelength is inversely proportional
Give a statement to prove this:

A

As frequency of a wave increases, wavelength decreases. This allows speed to stay constant for all electromagnetic waves.

48
Q

What are all electromagnetic waves produced by?

A

Produced by accelerating charged particles, especially electrons

49
Q

What is the formula that involves, speed of light, frequency and wavelength?

A

c = f x λ

*c is speed of light, 3 x 10^8 m.s^-1

*f is frequency, Hertz (Hz)

*λ wavelength, meters (m)

50
Q

What is ionisation?

A

The process of breaking an electron away from an atom

51
Q

What is non-ionizing radiation?

A

Radiation that does not have enough energy to break an electron way from an atom

52
Q

Why is ionizing radiation dangerous?

A

Ionizing radiation has enough energy to break an electron away from an atom.
This means ionizing radiation has the ability to change the chemical composition of the material it comes into contact with (causes mutations in DNA molecules)

53
Q

What are the only 2 types of electromagnetic radiation that is ionising?

A

Gamma rays
X-rays

Physics Theory (14 decks)

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