P1 Flashcards
What is a wave?
A regular disturbance that transfers energy
What is the amplitude of a wave?
The distance between the rest position and crest or trough
What is the wave length of a wave?
The distance between the same point on two neighbouring disturbances (one full cycle)
What is the frequency of a wave?
The number of complete waves placing through a point per second (measured in Hz)
What is the period of a wave?
The time it takes to complete one cycle- it is inversely proportionate to frequency
What is the medium of a wave?
Any substance that carries the wave, or through which the wave travels
What are some examples of transverse waves?
EM waves, S waves, Waves in water
What are some examples of longitudinal waves?
Sound waves, P waves
What direction is the disturbance of the medium to the direction of the wave in transverse waves?
Perpendicular (at 90 degrees)
What direction is the disturbance of the medium to the direction of the wave in longitudinal waves?
Parallel
In longitudinal waves, what is the point of high pressure (lots of particles) called?
Compressions
In longitudinal waves, what is the point of low pressure (fewer particles) called?
Rarefactions
What is the formula for wave speed?
Wave speed (m/s) = Frequency (Hz) x Wavelength (m)
What apparatus can you use to measure the speed of sound?
An oscilloscope, a speaker attached to a signal generator and two microphones
Describe the experiment to measure the speed of sound
1) Set up the oscilloscope so the detected waves at each mic are shown as separate waves
2) Start with both mics next to the speaker, then slowly move one away until the waves are aligned on the display, but have moved exactly one wavelength apart
3) Measure the distance between the two mics to find the wavelength
4) The frequency is whatever you set the signal generator to
5) Use the formula [Wave speed (m/s) = Frequency (Hz) x Wavelength (m)] to find out the speed of the wave (sound)
What are the 3 things that can happen when a wave meets a new boundary?
It can be absorbed, transmitted or reflected
What is it when a wave is absorbed?
The wave’s energy is transferred to the new material, often causing heating
What is it when a wave is transmitted?
The wave carries travelling through the new material, often causing refraction
What is it when a wave is reflected?
The wave is sent back away from the new material
What is the relationship between angle of incidence and angle of reflection?
Angle of incidence = Angle of reflection
What is refraction?
A change in the speed of which the wave is travelling, which when at an angle to the normal, causes a change in direction
Can the frequency of a wave change?
No
If the wave slows down, what is the effect on the wave length and why?
The wave length will also decrease, as speed = frequency x wavelength, therefore if speed decreases, and frequency cannot change, the wavelength must also decrease
If the wave speeds up, what is the effect on the wave length and why?
The wave length will also increase, as speed = frequency x wavelength, therefore if speed increases, and frequency cannot change, the wavelength must also increase
What is the normal?
A line drawn at a right angle to the boundary
What is the relationship between wavelength and frequency of EM waves?
As wavelength increases, frequency decreases
What is the wavelength of radio waves?
1m - 10^4 m
What is the wavelength of micro waves?
10^-2 m
What is the wavelength of infrared waves?
10^-5 m
What is the wavelength of visible light waves?
10^-7 m
What is the wavelength of ultra violet waves?
10^-8m
What is the wavelength of x-ray waves?
10^-10