Waves Flashcards
Why does the direction the wave is travelling tell you about the direction the energy is going
The direction of travel of the wave is the direction at which the wave transfers energy
What are waves used to transfer
Energy and information
What are the two types of wave
Transverse and longitudinal
What is the direction of energy transfer for a transverse wave
Perpendicular to the direction at which the wave travels
What direction does a longitudinal wave travel
Parallel to the direction of energy transfer
What is a longitudinal wave made up off
Compression and rarefactions
Give an example of a mechanical wave
Waves on springs
How do mechanical waves travel
As transverse or longitudinal waves
Why are all electromagnetic waves transverse waves
Because there are no moving particles in a electromagnetic wave, so the oscillations are perpendicular to the direction of travel.
What kind of wave are sound waves
Longitudinal
What type of wave can be produced on a piece of stretched spring
Transverse, mechanical waves
What is the amplitude of a wave
The distance between the height of the wavelength (peak) and the position at rest
In terms of energy, what does increasing the amplitude mean
It increases the amount of energy a wave carries
What is the wavelength of a wave
The distance for one crest to the next crest, or from one trough to the next
What is the frequency of a wave
The number of wave crests passing a point in one second
What is the unit for frequency
Hertz, Hz
What is the wavelength for a longitudinal wave
The distance from the middle of one compression to the middle of the next compression
How do you tell the frequency of longitudinal waves
The number of compressions passing a certain point in one second
Why is an image seen in a mirror
Because of the reflection of light
What is the “normal”
Straight line through a surface or boundary perpendicular to the surface boundary
In reflection the angle of incidence should be equal to
The angle of reflection
Describe the image formed in a mirror
- the same size as the object
- upright
- the same distance behind the mirror as the object is in front
- virtual
What is a real image
An image that can be formed on a screen because rays of light that produce the image can actually pass through it
What is a virtual image
It can be formed on a screen because the rays of light that produce the image only appear to pass through it
What happens to light waves when they cross a boundary
They speed up, the wavelength changes but the frequency stays the same
When does light refract
When it crosses a boundary such as air or water
Can all waves diffract
Yes
What causes waves to change direction during refraction
The change in speed
What happens to the speed of the wave when it enters a more dense object
It slows down and the ray changes direction towards the normal
What happen when light enters a less dense object
It speeds up and moves away from the normal
When will a wave not change direction
If it is travelling along the normal
Why does refraction take place
When light crosses a boundary
Which light is refracted the most
Violet light
Which light spectra is least refracted
Red light
Why does light split up into different colours when it passes through a triangular prism
Because different wavelengths of light are refracted by different amounts
What is diffraction
The spreading of waves when they pass through a gap or round an obstacle
Why don’t we see the diffraction of light in everyday life
Because the wavelength of light is too small
What kind of signals are carried by radio waves
TV signals
Why may people in hilly areas not be able to receive TV signals
Because the signal gets blocked by a hill
What sort of waves are diffracted
All types of waves are diffracted
What is sound caused by
Mechanical vibrations in a substance
In what state does sound travel through best
Solids
In which state does sound travel slowest
Gases
What is the range of human hearing
20Hz- 20,000Hz
What is a reflected sound wave called
Echoes
What sort of surfaces reflect sound
Hard, flat surfaces such as walls or floors
What sort of surfaces absorb sound
Soft furniture: carpets, curtains and furniture
Where does refraction take place
At the boundaries between layers of air at different temperatures
What does the pitch of a note depend on
The frequency of the sound waves
What effect does increasing the frequency have
The higher the pitch
What does the loudness of an instrument depend on
The amplitude of the sound waves
Why does increasing the amplitude have this effect on sound
Because the greater the amplitude, the more energy the wave carries and the louder the sound
What piece of equipment shows waves
An oscilloscope
Why do different instruments sound different when they play the same note
The waveforms are different
What produces a pure sound
Tuning fork and signal generators
What controls the quality of an instrument
The waveform
How does a flute make sound
The air in the pipe vibrates as you blow onto the mouthpiece
