# P1c: Spectrum of Waves

What are the four main features of a wave?
Trough, crest, amplitude and wavelength
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How do you work out wave speed?
frequency x wavelength
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Where do all electromagnetic waves travel at the same high speed?(2)
In a space/vacuum.
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Through a particular medium, how do electromagnetic waves travel?
in a straight line
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What does refraction involve?
A change in direction of a wave due to the wave passing from one medium into another
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Name the seven types of electromagnetic waves that compromise the spectrum and put them in ascending order of frequency
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Describe an example of a communications use for radio waves
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Describe an example of a communications use for microwaves
Microwave radiation can be used to transmit signals such as mobile phone calls.
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Describe an example of a communications use for infrared
Infrared radiation is used to transmit information from place to place: remote controls for television sets and DVD players, and data links between computers.
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Describe an example of a communications use for visible light
Visible light is the light we see.It allows us to communicate with 1 another through books,hand signals&video.The use of visible light needs the transmitter&receiver to be in line of sight,but it's more secure against eavesdroppers than radio waves.
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What is frequency?
the number of complete waves, cycles, or oscillations per second.
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What is wavelength?
The wavelength of a wave is the distance between a point on one wave and the same point on the next wave. It is often easiest to measure this from the crest of one wave to the crest of the next wave.
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What is amplitude?
As waves travel, they set up patterns of disturbance. The amplitude of a wave is its maximum disturbance from its undisturbed position.
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What is crest?
The top of the wave
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What is trough?
The bottom of the wave
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When does refraction occur at the boundary between mediums?
When it meets the boundary at an angle.
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Complete the sentence: Waves travel at _______ speeds in substances which have different _________
Waves travel at different speeds in substances which have different densities.
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What happens if a wave meets a boundary at 90 degrees?
It slows down but carries on in the same direction. It now has a shorter wavelength but the same frequency
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What happens if a wave meets a different boundary at an angle?
Part of the wave will hit the denser layer first and slows down, while another part carries on at the first, faster speed for a while. So the wave changes direction - its been refracted.
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Name the seven types of electromagnetic waves that compromise the spectrum in order of longest wavelength to shortest
Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, Gamma rays
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What is the law of reflection?
the angle of incidence equals the angle of reflection.
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What do smooth surfaces produce/act as?
Smooth surfaces produce strong echoes when sound waves hit them, and they can act as mirrors when light waves hit them. The waves are reflected uniformly and light can form images.
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In a plane (flat) mirror, where does the image appear to be?
behind the mirror
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What does diffraction reduce the quality of?
Diffraction reduces the quality of images seen in microscopes and telescopes. It can cause rings or spikes around the image of the object being viewed.
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What is diffraction?
When waves meet a gap in a barrier, they carry on through the gap. However, the waves spread out to some extent into the area beyond the gap.
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What does a gap much larger than the wavelength cause? Give an example
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What does a gap similar to the wavelength cause? Give an example.
a lot of spreading with no sharp shadow eg sound through a doorway
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When is the only time significant diffraction happens?
Significant diffraction only happens when the wavelength is of the same order of magnitude as the gap.
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## Other cards in this set

### Card 2

#### Front

How do you work out wave speed?

#### Back

frequency x wavelength

### Card 3

#### Front

Where do all electromagnetic waves travel at the same high speed?(2)

### Card 4

#### Front

Through a particular medium, how do electromagnetic waves travel?

### Card 5

#### Front

What does refraction involve?