physics chapter 13 Flashcards
(28 cards)
what is the electromagnetic spectrum
the electromagnetic spectrum is arranged in a specific order based on the wavelengths or frequencies of radiation in each region.
what are the main regions of the continuous electromagnetic spectrum from longest to shortest wavelengths
- radiowaves
- microwaves
-infrared
-visible - ultra violet
- x ray
- gamma rays
how can we calculate the speed of light
speed of light = frequency x wavelength
what are the properties that all electromagnetic haves share
- they are transverse
- can travel through a vacuum
- travel at the same speed in a vacuum
- form a continuous spectrum
what is electromagnetic radiation
electromagnetic waves transfer energy as they move. the term radiation usually used to refer to the energy being transferred.
what is the use of microwaves
- to cook
- radar system
what is the use of visible light
- vision
- photosynthesis
- photography from camera
what is the use of radiowaves
- tv and radio broadcasting
- telecommunication
what is the use of infrared waves
- night vision
- remote control
- alarm system
what is the use of gamma rays
- sterilising food
- treatment of cancer
what is the use of ultraviolet
- to kill bacteria of microbes
- sterilising water
what is the use of xrays
- kill cancer cells
- to take x ray picture
- detects flaws or cracks in a structure
what is the danger of radiowaves
no known danger
what is the danger of microwaves
internal heating of cells
what is the danger of infrared waves
skin burns
what are the harmful effects of excessive microwave exposure
- certain frequencies of microwaves are absorbed by water molecules
- humans contain lots of water so there is a risk of internal heating from the microwaves
what is the danger of ultraviolet
damage surface cells and eyes lead to skin cancer and eye conditions
what are the dangers of x ray and gamma rays
mutation or damage o cells in the body
what are the harmful effects of excessive xray and gamma ray exposure
- penetrate the body and cause internal damage
- can cause the mutation of dna, causing cancer
what are the harmful effects of excessive ultra violet exposure
- can kill cells and cause them to malfunction
- similar to visible light, except is invisible to the human eye and carries more energy
how fast to electromagnetic waves travel
all electromagnetic waves travel at the same speed of 3x10^8 m/s in a vacuum
how is wireless communication possible
the invisible radio waves and microwaves allow us to communicate wirelessly, there is no need to use a physical cable to link the transmitter and the receiver
for what is low orbit satellites used for
- used for the monitoring of the weather, military applications and taking images of the earths surface
for what is the geostationary satellites used for
used for telecommunication broadcasting around the world due to its high orbit
