Electromagnetic Waves Flashcards
what is the main difference between mechanical waves and electromagnetic wave
- mechanical waves are initiated by vibrating objects passing one some of their energy to the atoms or molecule of a material medium
- whereas electromagnetic waves are created when charged particles are accelerated
what is produced if electrons in an aerial are made to oscillate using electronic circuitry
- a wave of continuously varying electric and magnetic fields
- with the same frequency as the oscillator
what is the difference between how the electric and magnetic field oscillate
- the electric field oscillations are in the plane of the antenna (horizontal)
- whereas the magnetic field oscillations are in the plane at right angles to it (vertical)
can electromagnetic waves travel through a vacuum and why
- they can
- because they dont require a material medium to oscillate through
what is the relationship between the electric and magnetic fields other than the direction they oscillate in
one cannot exist without the other
why can electromagnetic waves be detected when they pass over charged particles
- because some of their energy is transferred to the particle
- which makes them vibrate at the frequency of the wave
how could electromagnetic waves be created from atoms
- by the quantum jumps of electrons in atoms
- or by excited nuclei
what kind of electromagnetic wave is emitted from an atom and what is it
- a photon is emitted
- they are bundles of waves a few nanoseconds in duration that have wavelengths dependent on their energy
what are the seven types of electromagnetic waves
- radio waves
- microwaves
- infrared radiation
- visible light
- ultraviolet
- x-rays
- gamma rays
how do the wavelengths of the waves change as you progress from radio waves to gamma rays
- the wavelengths decrease
what does the speed of a wave depend on
- the nature of the wave
- the medium is it passing through
what relationship can be drawn between the wavelength of a wave and its cycles that could be used to calculate its velocity
a wave will travel the distance on one wavelength in the time it takes for one cycle to be completed
what equation can be derived from that using the symbols for velocity, wavelength and period
v = lambda / T
what is the relationship between frequency and the period
- the frequency is equivalent to one over the period
- on other words, f = 1 / T
how would you replace the period in the equation with frequency
- v = f x lambda
- velocity = frequency x wavelength
