Waves Flashcards
For a longitudinal wave where do the oscillations move in relation to the direct in which the wave travels?
The oscillation of the particles is parallel to the direction of travel, of the wave
What is a longitudinal wave made up of?
Compressions and rarefactions
What are electromagnetic waves?
They can travel through a vacuum there are no particles moving in an electromagnetic wave as these waves are oscillations in electric and magnetic fields the oscillations are perpendicular to the direction of travel of the wave. So all electromagnetic waves are transverse waves.
Are electromagnetic waves transverse or longitudinal?
Transverse
What are mechanical waves?
E.g waves on springs and sound waves, travel through a medium (substance) mechanical waves may be transverse or longitudinal
Are mechanical waves transverse or longitudinal?
Either
Are sound waves longitudinal or transverse?
Longitudinal
When a longitudinal wave passes through air, what happens to the air particles at a compression?
They are pushed closer together
What is the amplitude?
Is the heigh of a wave crest or the depth of the wave trough from the position at rest
The greater the amplitude…
The more energy it carries
What is the wavelength?
The distance from one crest to the next crest or from one though to the next trough
What is the frequency?
The number of wave crests passing a point in one second
What is the unit of wavelength?
Metres
What is the unit or frequency?
Hz
What is the unit of wave speed?
M/s
What is the wavelength of a longitudinal wave?
Distance from the middle of one compression to the middle of the next compression or the middle of one repaired action to the middle of the next
What is the frequency of the longitudinal wave?
The number of compressions passing a point in one second
Why is an image seen in a mirror?
Because the reflection of light
What is the incident Ray?
The Ray that goes towards the mirror
What is the reflected Ray?
The Ray coming away from the mirror
What is the normal?
A line perpendicular to the mirror where the incident Ray hits the mirror
For the reflected Ray the angle of incidence…
Is equal to the angle of reflection
The image in a plane mirror is:
The same size as the object
Upright
The same distance behind the mirror as the object Infront
Virtual
What is a real image?
One that can be formed on a screen, because the rays of light that produce the image actually pass through it
What is a virtual image?
One that cannot be formed on a screen, because the days of light that produce the image only appear to pass through it
What size is the image in a plane mirror?
The same size as the object
What happens when a wave crosses a boundary between different substances?
The waves change speed, the wavelength changes but the frequency stays the same
What is refraction?
The change of direction of a Ray when it crosses a boundary between two transparent substances
Which waves dos refraction occur in?
All waves
What causes a change in direction in refraction?
The change in speed
What happens when light enters a more dense substance?
Eg going from air to glass, it slows down the Rays and the Ray changes direction towards the normal
What happens when light enters a less dense substance?
Eg glass to air the Ray speeds up and the Ray changes direction away from the normal
Regardless of density of the substance it enters, is the wave travels along the normal will it change direction?
No
What is it called when light splits up I to the spectrum in a prism?
Dispersion
Which colour of light is refracted the most?
Violet
What colour of light is refracted the least?
Red light
Why does light split up into different colours when it passes through a triangular prism?
Because different waves of light have different wavelengths
Diffraction is a property of which waves?
All
When is the effect of diffraction most effective?
When the wavelength of the waves is about the same size as the gap or the obstacle
Why don’t we observe the diffraction of light in everyday life?
Because the wavelength of light is very short
What is a practical every day example of diffraction?
If radio waves do not diffract enough when they go over hills, radio and to reception will be poor
What is sound caused by?
Mechanical vibrations
How does sound travel?
As a wave
In what does sound travel fastest?
Solids
Can sound travel through a vacuum?
No
Where is the direction of a sound wave in relation to the direction in which the wave travels?
Same direction
What is the range of human hearing?
20- 20,000 Hz
Where can sound waves be reflected to produce echoes?
Hard flat surface as they reflect sound
Soft carpets, absorb sounds
An empty too will sound different once it has been furnished
What does the refraction of sound depend on?
The boundaries between layers of air at different temperatures
What does the pitch depend on?
The frequency, the higher the frequency the higher the pitch
What does loudness depend on?
The amplitude
How does amplitude affect volume?
The greater the amplitude of the wave the more energy it can carry so the louder it is
What does the quality of a note depend on?
The waveform
When aninstrument is played what is produced?
Vibrations
Why do instruments sou different?
They produce different waveforms
For a transverse wave where do the oscillations move in relation to the direct in which the wave travels?
The oscillation or the particles is perpendicular to the direction at which the wave travels