Waves Flashcards
Label the number on the graph
1 - Amplitude
2 - Peak
3 - Trough
4 - Wavelength
5 - Displacement
6 - Distance
7 - Compression
8 - Rarefaction
What is amplitude
The maximum disturbance of a wave from its undisturbed position
What is wavelength
The distance from a point on one wave to the same point om the next wave, measured in metres
What is compression
Waves in a longitudinal wave which are close together
What is rarefaction
Waves in a longitudinal wave which are far apart
What is time period
The time for a single wave to happen
What is wave speed
The speed at which the wave moves
What is frequency
The number of waves passing a point each second
What is the equation linking time period, frequency and 1
T = 1/f
T - Time period, measured in seconds (s)
F - frequency, measured in hertz (Hz)
What is the equation linking wave speed frequency and wave length
v = fλ
v - velocity, measured in metres per second (m/s)
f - frequency, measured in hertz (Hz)
λ - wavelength, measured in metres (m)
Required practical : Measuring waves in a ripple tank
What is the method
Place the ripple tank on a table over a piece of paper
Fill the tank with a bit of water
Attach the dipper to a power supply
Turn the dipper on, start a timer, record in slow motion for ten seconds and take a screenshot of the video
Find the wavelength by measuring the distance between the peaks
Find the frequency by counting the number of waves in the video and divide it by 10
Find the wave speed by multiplying the frequency by the wave length
What is the difference between transverse and longitudinal wave
Transverse - oscillations are perpendicular to the direction of energy transfer, e.g. light
Longitudinal - oscillations are parallel to the direction of energy transfer, e.g. sound
What are the EM waves
Radio waves
Microwaves
Infrared
Visible light
UV
X-rays
Gamma rays
What are the properties of EM waves
They travel at the speed of light
They can travel through a vacuum
They transfer energy
They are transverse waves
They obey the wave equation
What are the uses of EM waves
Radio waves - transmit radio and TV programmes between different points on the Earth’s surface
Microwaves - heat substances, mobile phones to communicate with satellites
Infrared - night vision cameras
Visible light - to see things
UV - sunbeds
X-rays - produce shadow pictures of materials
Gamma rays - sterilise surgical equipment, kill cancer cells
What are the dangers of EM waves
UV - cause mutations, cancer, skin to age prematurely, increases the risk of skin cancer
X-rays and gamma rays - cause mutations, cancer, damage human tissue
What is the angle of incidence
The angle between the normal and incident ray
Define angle of reflection
The angle between the normal and reflected ray
What is normal
An imaginary but useful line at right angles to the boundary between air/glass. All angles are measured to this line
What’s the difference between specular and diffuse reflection
Specular - light travels towards a surface in one direction and is reflected in a single direction
Diffuse - light travel towards a surface and is scattered in different directions
What is refraction
When a wave goes through a substance and its speed and direction changes
Low density —> high density (air —> substance
High density —> low density (substance —> air)
Required practical : How different surfaces affect infrared intensity
What is the method
Place a Leslie cube on a heat-resistant mat
Fill it, almost to the top, with boiling water and replace the lid
Leave for one minute
Use the infrared detector to measure the intensity of infrared radiation emitted from each surface, or the temperature of the surface. Make sure that the detector is the same distance from each surface for each reading
