Waves Flashcards
Define amplitude
Maximum displacement from equilibrium position (m)
Define period of an oscillation
The time taken for one oscillation (s)
Define displacement
Distance form the equilibrium position in a particular direction; can have a positive or negative value (m)
Define phase difference
The difference between displacement of particles along a wave
Define frequency
The number of waves passing a certain point per unit time (hz)
Define wave speed
The distance travelled by the wave per unit time
What is a longitudinal wave
A wave where the direction of oscillation travels parallel to direction of motion. It is made up of compressions and rarefactions.
What is a transverse wave
Is a wave which it is direction of oscillation is perpendicular to the direction of motion.
What is the equation for wave speed
V=fλ
Equation for frequency
F=1÷Period of oscillation
Define intensity
The radiant power passing through a surface per unit area measured in (Wm⁻²)
Equation for intensity
Intensity = power/area
What is reflection
When the waves bounces back when it hits a boundary. The angle of incidence is always equal to the angle of reflection.
What is refraction
The bending of light as it passes from one medium to another. The amount of refraction depends on the refractive index of the material.
What is the equation for refractive index
Speed of light in vacuum/speed of light in material
N=C/V
What is snells law
n₁sinθ₁=n₂sinθ₂
Equation to find the critical angle
SinC=1/n
Where C is the critical angle
What is the wavelength of radio waves
10⁻¹ to 10⁶
What is the wavelength of microwaves
10⁻³to 10⁻¹
What is the wavelength of infrared
7x10⁻⁷ to 10⁻³
What is the wavelength of visible light
4x10⁻⁷ to 7x10⁻⁷
What is the wavelength of ultraviolet
10⁻⁸ to 4x10⁻⁷
What is the wavelength of x-rays
10⁻¹³ to 10⁻⁸
What is the wavelength of gamma rays
10⁻¹⁶ to 10⁻¹⁰
What do all electromagnetic waves have in common
- All travel at the speed of light
- They are all transverse waves
- They all travel through a vacuum
- They all travel in straight lines
- Electromagnetic waves with a higher frequency have higher energy while low frequency has low energy.
- They can diffract, refract, reflect
What is polarised light and what is unpolarised light
Polarised light in when light oscillated in one plane of movement
Unpolarised light is when light oscillates in many different planes
What type of waves can be polarised
Only transverse waves
Describe an experiment to show polarisation
Have an emitter emitting an transverse waves.
Have two filters orientated the same way, there should be only one plane of movement.
As you rotate one filter the intensity will decrease and will become 0 when filters orientation are perpendicular.
You will measure intensity with a receiver.
What is superposition
When two waves of the same type meet and pass through each other. Where they overlap they produce a single wave. The resultant wave will be the displacements added together.
What is total constructive interference
Is when the resulting wave is twice the original wave because the two waves are completely in phase 0, 2π, 4π
What is total destructive interference
Is when the resulting wave amplitude is 0 because the two waves are in anti phase π, 3π, 5π
What is diffraction
The spreading out of a wave as it passes through an aperture or obstacle
When does greatest diffraction occur
λ=a greatest diffraction
λ>a notice diffraction
λ<a></a>
Young’s double slit experiment conditions and the equation
- Light must be monochromatic
- Light must be coherent (constant phase difference)
- Path difference must be 1λ to make a bright fringe
λ=ax/d
What is diffraction gratings
Is when you shine white light through a diffraction grating produce dark and bright fringes. However where there is a bright fringe it shows the spectrum.
What is a stationary wave
A stationary wave is the superposition of two progressive waves with the same wavelength moving in opposite directions.
No energy is transmitted it is stored.
What is a node
Points on the stationary wave at which there is no amplitude of the particular at any time.
What is an antinode
Points on a stationary wave of maximum amplitude
How are stationary waves different to progressive waves
In stationary waves energy is stored, in progressive energy is transmitted.
In progressive waves all parts have the same amplitude but in stationary they are arm different.
What is the first harmonic in terms of wavelength
It is half a wave length
What is the first harmonic in a closed tube
1/4 wavelength of a stationary wave.
How to determine the speed of sound
- Create a closed end pipe by placing a hollow tube in water.
- Get a tuning fork and hold it above the tube.
- Move the tube up and down until you find the shortest distance between the tube and the water level that the sound resonates the loudest.
- This would be a quarter wavelength. Find the full wavelength by multiplying the length by 4.
- Then use equation V=fλ
