# Waves

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• Created by: Heather
• Created on: 27-05-14 18:19
What are waves?
Waves are vibrations that transfer energy from place to place without matter being transferred,
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What is the substance know as that travels through a substance?
The Medium
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Give an example of a wave that have to travel through a substance?
Sound waves or seismic waves
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Give three examples of waves that dont have to travel through a substance?
Visible light, infrared rays, microwaves, ultraviolet waves, x-rays,
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What are transverse waves?-Describe the oscillations?
Transverse waves have oscillations that are at right angles to the direction of travel and energy transfer,
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What are longitudinal waves?-Describe the oscillations?
In longitudinal waves, the oscillations are along the same direction as the direction of travel and energy transfer,
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What is the definiton of an amplitude?
The amplitude of a wave is its maximum disturbance from its undisturbed position at 0.
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What is the definition of a wavelength?
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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What is the fequency of a wave?
It is the number of waves produced by a source each second-The number of waves that pass a point per second,
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What is the unit of frequency?
Hertz-Hz or Kilohertz-kHz
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What is the unit for the wave speed?
Metres per Second-m/s
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What is the unit of the wave length?
metres, m
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Why does refraction happen?
As when sound and light waves enter a different medium and cross the boundary, they change speed which causes them to change directiion,
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What is the exception of changing direction in different mediums?
Doesnt happen if the wave crosses the boundary at an angle of 90 degrees,
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When does diffraction happen?
When waves meet a gap in a bairrier, they carry on through the gap but waves spread out in the area beynd the gap
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What does the extent of the spreading depend on?
The width of the gap comapred to the wavelenth of the wave,-Large wavelength=little spreading,
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What is the law of reflection?
Angle of incidence=angle of reflection
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What kind of surfaces produce a strong echoes when soudn waves hit them?
Smooth surfaces,
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What is the definition of virtual images?
They can't be touched or projected on a screen,
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What are the imaegs reflected from a plane mirror described as? (3)
-Virtual, upright, laterally inverted
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What kind of waves are sound waves?
Longitudinal-Vibrations occur in line of energy transfer and direction of travel,
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When objects vibrate, what makes the vibration louder on the wave?
A greater amplitude,
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When objects vibrate, what makes the vibration's pitch higher on the wave?
A greater frequency,
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What is the range of human hearing?
20Hz to 20,000Hz/20kHz
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What is sound with frequencies above 20Khz called?
Ultrasound,
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what can make white light spilt up to form what?
Using a prism to form a spectrum
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How does a prism work?-
The prism is a different density tio the air so the light rays are refracted when entering and leaving the prism in its wavelengths-
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Describe how wavelenth forms the prism and which colour has what?
Light waves split to form a spectrum due to their wavelength. the shorter their wavelength, the more they are refracted so violet light is refracted most as it has the shortest wave length and red light is refracted least, causing a soloured spectrum
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What are the properties of radiowaves comapred to other waves in electromagnetic spectrum?
They have the lowest energy, lowest frequency, and the longest wavelength
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What are the properties of gamma radiation comapred to other waves in electromagnetic spectrum?
They have the highest energy, the highest frequency and the shortest wavelength,
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What are radio waves used for?
They are used to transmit television and radio programmes,
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What allows low-frequency radio wves to be revieved over the hills?
Diffraction-Its allows radio recievers to not need to be directly in view of transmitter to recieve signals,
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What are microwaves used for?
Used to transmit signals such as mobile phone calls
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Althoug microwaves are seen as dangerous, why do some peoplenot agree?
The intensity of the microwaves for phones are too low to damge cell tissues and ae not ionising,
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What does visible light allows us to do?
Communicate-hand signals, video, books etc,
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Although we cant see infrared radiation, how do we know its there?
By the hear energy produced,
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What is infrared used in?
They are used in senors to detect heat from the body like security alarms and burglar alarms. Also in remote controls for tv,
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## Other cards in this set

### Card 2

#### Front

What is the substance know as that travels through a substance?

The Medium

### Card 3

#### Front

Give an example of a wave that have to travel through a substance?

### Card 4

#### Front

Give three examples of waves that dont have to travel through a substance?

### Card 5

#### Front

What are transverse waves?-Describe the oscillations?