nature and sources of light
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what are the 2 types of light?
natural artificial
light
the only form of energy that can travel like a wave through empty space and through some materials
what kind of wave does light behave like?
electromagnetic
can you see electromagnetic waves?
no, they are invisible
electromagnetic waves can travel through a ______ at the ______
vacuum / speed of light
what is the speed of light?
3 x 10 to the power of eight m/s
wavelength
distance from the peak of one wave to the peak of the next wave
frequency
number of complete wavelengths that pass a given point in one second
electromagnetic spectrum
diagram that illustrates the arrangement of electronic waves according to wavelength or frequency
low energy= ____ wavelength
long
high energy= ____ wavelength
short
visible light
any electromagnetic wave that the human eye can see
visible spectrum
continuous sequence of different colours together form visible white light
luminous source of light
gives off its own natural light
artificial source of light
production of light by converting external energy forms (chemical, electrical, thermal)
non-luminous source of light
does not give off its own light, may appear bright because of reflection from a luminous object
what are 3 types of light emission?
from the sun from incandescence from electric discharge
light from the sun: fusion reaction: ______ atoms in the sun’s core collide and sometimes ___________
hydrogen / combine or fuse to form
light from the sun: tremendous amounts of ______ is released
energy
light from the sun: energy transmitted to the bases on _________
outer layers of sun
light from the sun: excited atoms release ___________
excess energy
light from the sun: _____ is emitted
light
light from incandescence
a light emitted by a very hot object
incandescent bulbs are very inefficient at producing light. how much energy used becomes light versus how much energy is lost as heat?
5% light / 95% heat