Waves, Electricity and Magnetism Flashcards
Define Waves
An oscillation that carries energy and information from one place to another
What are different types of waves?
- Travelling
2. Stationary
What can travelling waves be?
- Longitudinal
2. Transverse
What are the different shapes of wave?
- Sine wave
- Square wave
- Triangle and sawtooth wave
What are longitudinal wave?
Oscillation of the particle go parallel to the direction of propagation of the wave
What are examples of transverse waves?
Ripples on surface of water
What are examples of longitudinal waves?
sound waves travelling in the air
What are transverse waves?
Oscillations are perpendicular to the direction of wave propagation
Transverse waves
The oscillations are up and down but the direction of energy transfer is sideways
Longitudinal wave: how does sound waves travel?
Particles in air
move from side to side
What do all longitudinal wave require?
A medium to travel in e.g. air, liquid and solid
What are examples of transverse waves from a medical perpesctives?
- X-ray - lateral x-rays of the skull
- NIRS
- Radiowaves
What are examples of properties of waves?
- Amplitude
- Wavelength
- Frequency
- Period
Define amplitude
The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position
What is amplitude?
The furthest point the wave vibrates from this undisturbed position
What is wavelength of wave?
Distance from a point on one wave to the equivalent point on the adjacent wave
Wavelength
Take a point on one wave e.g. the top then measure the distance to the same point on the next wave then that is the wavelength
what is the symbol for wavelength ?
Greek letter lambda
what is the frequency?
The number of waves passing a point each second
What is unit of frequency?
Hertz (Hz)
1 Hz = 1 wave per second
What is the period?
Time (in seconds) for one wave to pass a point
What is equation of period?
1/Frequency T=1/f
What are the examples of wave behaviour?
- Interference and superposition
- Reflection
- Refraction
- Diffraction
What is interference?
Combined effect of the disturbance caused by each individual wave at the same place and at same time
What is the principle of superposition?
When two or more waves travel through the same medium simultaneously, the resultant displacement at any point is the vector sum of the displacement due to the individual waves
What is standing waves?
When two waves of the same frequency travelling in opposite directions add together
observed in microwave ovens
What is speed of light?
Constant in a vacuum
3x10ms-1
What is wavelength of electromagnetic rod
speed of wave/frequency
What are 2 ways of reflection?
- Specular
2. Diffuse
What can the surface of a material do?
Transmit, absorb or reflect a wave
What is specular reflection?
Angle of incidence = Angle of reflection e.g. light on mirror
What is diffuse reflection?
Reflection of wave from a surface in which the incident wave is reflected at multiple angles
What is refraction?
The change in direction of propagation of a wave as it passes through different materials
What is diffraction?
A range of phenomenen observed when waves interact with slits, edges and other obstacles
What is electromagnetic waves?
Transverse waces
Transfer energy from the source of the waves to an absorber
What is a small part of the electromagnetic spectrum?
Visible light
What is example of low frequency and long wavelength?
Radiowaves
Microwaves
Infrared
What are examples of high frequency and short wavelength?
Visible light
Ultraviolet
X-rays
Gamma rays
Where does the wavelength decrease?
Radiowaves to Gamma rays
What are the sources of magnetic field?
Current in wire Loop of wire Solenoid Bar magnet The earth
What does the size and direction of force depend on?
Distribution of field lines
What is strength of magnetic field measured in?
Telsa
region of low flux density
weak field
