Waves Flashcards
What is wavelength
Distance between the same points on two consecutive waves
What is amplitude
distance between equilibrium line and maximum displacement
What is frequency
the number of waves that pass through a single point per second
What is a period
the time taken for a whole wave to completely pass a single point
What is the equation for wave length
Wave speed= frequency x wavelength
v= f (lamda)
What is the equation for a period of a wave
period = 1/frequency
T= 1/f
seconds= 1/ Hz
(time/number of waves)
What are the two types of waves
Transverse and longitudinal
What is a transverse wave?
Light or electromagnetic wave, has peaks and troughs, vibrates at a right angle to direction of energy transfer
What is a longitudinal wave
Sound wave, has compressions and rarefaction, vibrations are in the same direction as direction as energy transfer
What is key about a waves movement?
The wave moves not what it passes through.
How to measure velocity of sound in air?
Make a noise 50 m from a wall and record time for an echo to be heard. Then use speed = distance/time
How to measure velocity if ripples on water surface?
Use a stroboscope which has the same frequency as the water waves then measure distance between fixed ripple and use v= f x (lamda)
What happens to waves at boundaries?
They can be reflected absorbed or transmitted
When do waves reflect?
Off flat surfaces
Angle of incidence =
angle of reflection
When are waves transmitted?
Through transparent materials
When are waves absorbed?
If frequency of light matches energy of electrons
What happens when waves are absorbed?
The electrons absorb the light and remit it over time as heat
What can sound waves travel through
Gas liquid and solid as they cause vibrations
How do we hear sound?
Putter ear collects sounds
Travels down ear canal
Wave hits ear drum with same pressure to vibrate it
Small bones also vibrate at same frequency
Vibrations transmitted to ear canal
Small hairs lining cochlear move too for specific frequencies
What range of Hz can humans hear?
20Hz - 20 kHz
What’s an ultrasound?
When the wave reaches a boundary between 2 materials they are partially reflected back while the rest pass through.
What is ultrasound used for?
Distances or imaging under surfaces
What are P waves?
Longitudinal waves that pass through solids and liquids
What are S waves?
Transverse waves that only pass through solids and move slower
What are P and S waves used for?
Understanding the inside of the Earth
What is a sonar?
A pulse of ultrasound sent below a ship to work out depth
What are the electromagnetic waves?
Radio, Micro, Infrared, Visible, Ultraviolet, X-rays, Gamma
What are electromagnetic waves?
Transverse waves that don’t need particakes to move
What part of our eyes detects visible light?
Retina
What happens to refract a light wave?
Denser materials refract towards normal, less dense bends it away from normal
Why does dispersion of a white light occur through a prism?
Different wave lengths redact different amounts.
How are radio waves produced
Oscillations of electrical circuits
What is electromagnetic radiation?
When electrons change orbit?
What happens when the electrons move to a higher orbit?
The atom has absorbed EM rasiation
What happens when the electron falls to a lower orbit?
The atom has emitted EM radiation
What is a wave?
an oscillation or vibration passing through a medium
What is the movement of a wave caused by?
The individual particles of the medium moving/ oscillating around its rest position
What happens in longitudinal waves?
They have compressions and rerefaction
Equation for frequency of waves?
Frequency = number of waves/ time
1/t
What does speed of sound depend on?
The density and temp of material but can be considered constant on any day
What is equation for percentage uncertainty?
resolution/ value
half range/ mean x100
What is a black body?
An object that absorbs all the radiation it receives and also emits all types of radiation
