P13 Electromagnetic spectrum Flashcards
What are electromagnetic waves
transverse waves that transfer energy from a source to an absorber
what speed do EM waves travel through air or a vacuum
the same speed - the speed of light
what spectrum do electromagnetic waves form
a continuous spectrum over a range of frequencies
how can EM waves be grouped and ranked
in terms of frequency and wavelength into seven basic types
why is there such a wide range of frequencies for EM waves
because they are generated by a variety of hcnages in atoms and thier nuclei
what are EM waves caused by
something with an electrical charge osillating
what are the seven EM wave types
- radio waves
- microwaves
- infrared waves
- visiable light
- ultraviolet
- x-rays
- gamma rays
which EM wave has the smallest wavelength
gamma rays
which EM wave has the biggest frequency
gamma rays
which EM wave has the biggest wavelength
radio waves
which EM wave has the smallest frequency
radio waves
what are EM waves made up of
oscillating electric and magnetic fields
how can you produce radio waves using an alternating current in an electrical circuit
- the object with the charges (electrons) oscillate to create the radio waves is a transmitter
- when the transmitted radio waves reach a receiver they are absorbed
- the energy carried is transferred to the electrons in the reciever
- causing the electrons to oscillate ~ generating an alternating current
what are radio waves main use
communication
why can long-wave radio waves be recieved even if the receiver isn’t in the line of sight of the transmitter
because long wavelengths diffact (bend) around the curved surface of the Earth, hills or into tunnels
can short-wave radio waves be recieved from long distances and why
yes because they are reflected from the ionosphere
what is the ionosphere
an electrically charged layer in the Earth’s upper atmosphere
what type of radio waves does bluetooth use
short-wave radio waves
what are microwaves used for
satellite communication and microwave ovens
why are microwaves best for satellite communication
because they pass easily through the Earth’s watery atmosphere
how does satellite communication work
- signal from transmitter is transmitted into space
- picked up by satellite receiver dish
- satellite transmits the sign back down to earth
- it is received by a satellite dish on the ground
how do microwaves work in microwave ovens
- the microwaves are absorbed by the water molecules in the food
- transferring the energy to the water molecules causing the food to heat up