light and the electromagnetic spectrum Flashcards
(27 cards)
what do all electromagnetic waves have in common?
- all are transverse waves
-all travel at the same speed in a vacuum (3x10^8)
-transfer energy from a source to an observer
an example of a electromagnetic wave transferring energy from a source to an observer
all objects emitting infrared radiation, the more hotter the object the more radiation emitted
what is the electromagnetic spectrum in order
gamma rays
x rays
ultra violet
visible light
infrared
microwaves
radio wave
which ways does it increase in wavelength and frequency
gamma rays have the shortest wavelength and highest frequencies.
radio waves have the longest wave lengths and the shortest frequencies
uses and properties of radio waves
- lowest frequency
- longest wavelength
- used to transmit radio broadcasting and tv programmes
uses of micro waves
- used for communication and satellite transmissions and mobile phones
- to heat food in a microwave
dangers of micro waves
- heats water in food, when digested can cause internal heating of body cells
uses of infrared radiation
- can be used as communication at short distances
- security systems have sensors to detect infrared radiation which comes off of intruders
danger of infra red radiation
can lead to skin burns if there is too much contact
uses of visible light
- lightbulbs can made to emit visible light
- cameras made to detect visible light
uses of ultra violet
- detecting forged bank notes
- disinfecting water by killing micro organisms
- fluorescent lamps
the visible light spectrum
red ( closer to infrared/micro/radio)
orange
yellow
green
blue
indigo
violet ( closer to gamma)
dangers of using ultra violet
damage to surface cells and eyes, can lead to skin cancer and eye condition
uses of x - rays
- observing the insides of objects
- airport security scanners
- medical x -rays to see the conditions of the body
uses of gamma rays
- sterilise food and medical equipment
- the detection of cancer and to treat cancer
dangers of using x-rays and gamma rays
can cause mutations to cells and damage cells in the body
how does the body stay a constant temp. in relation to radiation
the body must absorb and radiate the same average power for radiation for the temperature of the body to stay the same
what happens if the body gives out more radiation and absorbs less radiation
- the body lets out more radiation
- so the temperature of the body will decrease
what happens if more radiation absorbed increases and the less radiation is emitted
- more radiation kept in the body
- so the earth will heat up
Explain the effects of differences in the velocities of electromagnetic waves in different substances
- Since the wave travels at different velocities in different substances
- this can lead to the wave changing direction
the earth energy balance
for the earth to stay the same temperature
it must radiate the same amount of energy as being let out into the atmosphere
explain the green house effect
-radiation from the sun reaches the earth surface
-some of the radiation is absorbed but most if reflected
- the some of the emitted radiation is absorbed by green house gases in the atmosphere
- this causes the earth to heat up
what do all the colours together make up
white light
what is specular reflection
where light is reflected evenly on very smooth surfaces.