P6 - Waves Flashcards
What are transverse and longitudinal waves
Transverse - oscillations that are perpendicular to energy transfer
Longitudinal - oscillations that are parallel to energy transfer
Give examples of transverse and longitudinal waves
Longitudinal waves - sound waves
Transverse waves - electromagnetic waves, ripples and waves in water, wave on a string
Describe what is meant by:
amplitude
wavelength
frequency
The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position.
The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave.
The frequency of a wave is the number of waves passing a point each second.
What do you measure the speed of sound
Oscilloscope
Describe how to measure the speed of water ripples using a ripple tank ( 6 marks)
Using a signal generator attached to the dipper of a ripple tank - create water waves at a set frequency
Dim the lights in the lab and turn on the lamp - wave crests as shadows appear below the tank
Distance between each shadow line is equal to one wavelength
Measure distance between 10 shadow lines then divide this by 10 - average wavelength
Use v=fw
What is the equation for period
1/f
Describe how the wave equation can be used for waves on strings (6 marks)
Turn on signal generator and vibration transducer - string will start to vibrate
Adjust the frequency of the signal generator until there’s a clear wave on the string
Frequency needed depends on the length of the string between pulley and transducer and masses used
Measure the wave length of these waves - 5 in one go - divide by 5 - mean half-wavelength
Double to get full wavelength
Frequency is what the signal generator is set to
Substitute to find speed using v=fw
What are electromagnetic waves (2 marks)
Electromagnetic waves are transverse waves that transfer energy from the source of the waves to an absorber.
How is the electromagnetic spectrum grouped
Going from long to short wavelength (or from low to high frequency)
Name all parts of the magnetic spectrum
ROMANIAN MEN IN VENEZUELA USING EXPENSIVE GUNS !
Radio waves - micro waves - infrared - visible light - ultra violet - x rays - gamma rays
What part of the electromagnetic spectrum can humans see
visible light fr.
What three things can all waves do
Absorbed
Transmitted
Reflected
What causes refraction
difference in velocity of the waves in different substances
What is bigger the angle of incidence or angle of refraction
angle of incidence
If the wave fonts are closer together what does it mean ( 2 marks)
Shows a change in wavelength and change in velocity
investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface ( 6 marks obvs)
Place an empty Leslie cube on a heat proof mat
Boil water in a kettle and fill Leslie cube
Wait for cube to warm up - hold thermometer against each of the four faces of the cube - (should be same temperature)
Hold an infrared detector 10 cm away from one of the cube’s vertical faces and record amount of IR radiation it detects
Repeat for each cube’s vertical face - position the detector at the same distance from the cube each time
More infrared radiation from the black surface than white
More from matt surfaces from shiny
Repeat experiment more than once
How can radio waves be produced
Radio waves can be produced by oscillations in electrical
circuits.
How can radio waves be produced
Radio waves can be produced by oscillations in electrical
circuits.
What are the hazards from ultraviolet and x rays
UV - Premature ageing of the skin and increase risk of skin cancer
X-rays - Ionising radiation that can cause mutations of genes and cancer
What are the uses of:
radio waves
microwaves
infrared
radio waves – television and radio
* microwaves – satellite communications, cooking food
* infrared – electrical heaters, cooking food, infrared cameras
