Week 3- Electromagnetic And Optical Radiation Flashcards
Define radiation
radiation is the emission or transmission of energy in the form of waves or particlesthrough space (a vacuum) or through a material medium (e.g. air
Define electromagnetic radiation
air)§ electromagnetic radiation: such as radio waves, microwaves, infrared, visible light,ultraviolet, x-rays, and gamma radiation (γ)§
Define particle radiation
(γ)§ particle radiation: such as alpha radiation (α), beta radiation (β), and neutron radiation§
Examples of acoustic radiation
§ acoustic radiation: such as ultrasound, sound, and seismic waves (dependent on aphysical transmission medium)§
Examples of gravitational radiation
gravitational radiation: radiation that takes the form of gravitational waves, or ripples in thecurvature of spacetime
What are all waves carried by
some form of oscillation, e.g. sound waves arecarried by oscillating gas molecules, and electromagnetic waves are carriedby oscillating electric and magnetic fields
Name forms in which waves appear
Sound, heat,light, x-rays
What is oscillation
Oscillation is the repetitive variation (typically in time) of some measureabout a central value (often a point of equilibrium
What is vibration
)§ Vibration is the term that is precisely used to describe mechanical oscillation
Name the 2 types of waves
Longitudinal
Transverse
What do longitudinal waves require
A medium through which to travel
What can’t longitudinal waves travel through
A vacuum
Describe longitudinal waves
Longitudinal waves require a medium through whichto travel (i.e. cannot travel through a vacuum).
The particles of the transmitting medium are displaced along the direction of propagation
Describe transverse waves
Transverse waves do not always require a medium through which to travel.
The displacement of any transmitting medium is perpendicular to thedirection of propagation
What is the amplitude
Largest displacement encountered during oscillation
What is the wavelength
Distance between two consecutive point (two peaks, two troughs)
What is the period
Period of an oscillation is the time taken to complete one cycle
What is the frequency of any oscilation
Number of cycles completed every second
What is frequency measured in
Herts
HZ
S-1
T= s
Give the equation to work out frequency
F= 1/t
T= 1/F
What is the speed
Unitdistance traveled by a cycle per unit of time
Give equations for speed
C=. Distance/ time
Wavelength/ time = speed
Wavelength x frequency
When can velocity change
When traveling from one medium to another
What has an inverse relationship with frequency
Wave length to allow speed to remain constant
How do electromagnetic waves travel
What do they exhibit
In a straight line
Rectilinear propagation
Define radiation intensity
§ The energy carried by a wave can be described by the concept of intensity (
I)§ Radiation intensity (I) is defined as the quantity of radiation energy passing though a unit-area per unit of tim
Give an equation to work out intensity
Energy per second/ area
Explain inverse square law
Total amount of radiation in beam doesn’t change
Conc (intensity) descreases with increasing distance from the source
What is thr EM spectrum
Electromagnetic radiation organised by frequency and wavelength in a sequential order
Grouped in many sub ranges (visible light, ultraviolet radiation)
Divisions identified by differences in behaviour, emission, transmission, absorption of corresponding waves
What is the energy of a photon proportional to
Wave frequency
what is an electronvolt
electron after it has been accelerated from rest through a potential difference of one volt
what is an electric current through an area defined as
the net charge flowing through any point of wire per unit time
give the equation to work out electric current
Q= I T
q= electric charge
i= electric current
t= time
when can an electrical current flow
when something pushes it
what is electrical voltage
the pressure that pushes the electrons within an electrical wire, allowing them to flow through the wire
where does the push for electron voltage come from
the difference in potential energy at the start and the end of an electrical circuit
