Electromagnetic Waves Flashcards
What is EM radiation caused by
By the acceleration of electrically charged particles
What does a charged particle produce when it accelerates
It produces a magnetic field around it
Why does the speed of the charged particle change
Because it accelerates, which changes the generated magnetic field
Why does light slow down when travelling through a medium
Because EM waves involve oscillating fields rather than particles. So when it travels through matter, the fields interact with the matter in different ways, some of which can be harmful
What is the relationship between frequency and wavelength
They are inversely proportional
The higher the frequency of the electromagnetic radiation, the lower the wavelength
Visible light
8×10(-7) m (red light)
4 × 10(-7) m (violet light)
What Is a photon
A packet of energy found in light
What us the energy of a photon given by
E = hf
Because h is constant. it follows that the energy of a photon is proportional to the frequency of the radiation
Dual nature of electromagnetic radiation
Some aspects of the behavior of electromagnetic radiation can be explained using a wave model and some aspects can be best explained using a particle modele
Properties of electromagnetic waves
Originate from accelerating electric charges
Propagate as electric and magnetic fields that are perpendicular to each other
Can travel through a vacuum
Have a speed of 3×10(8) m. S(-1)
Uses of electromagnetic waves
Radio waves - radio and television broadcasts
Microwaves - satellite communications and radar systems
Infrared - remote controls, optical fibers
Visible light - fibre optic communications
Ultraviolet - light bulbs and sterilization
X-rays - CT scans, security scans
Gamma rays - radiation of cancer
Penetrating ability
The higher the energy the greater the penetrating ability
The amount of energy is directly proportional to the penetrating ability
Dangers of gamma rays, x-rays
X-rays - damages the skin and underlying tissue
Gamma rays - damage to tissue and nuclear radiation
Damaging effect of ultra violet radiation on skin
It causes sun spots, tanning, sun burns and blistering which can lead to skin cancer
How does em wave propagte
An oscillating electric field in one plane produces an oscillating magnetic field perpendicular to it
