Planets are not hot enough, and that's because they lack the internal energy sources that stars have: thermonuclear fusion (They do emit a little light, mainly infrared light, but nothing compared to the sun)
Planets don't have their own light, so simply they do not emit light, this phenomena goes back to their information. When they are formed, they are much, much less hotter than the stars. In stars, fusion reaction always goes on, in which energy, as well as light is formed, so, there is light for stars to emit for a long time.
By definition, when the speed of the light changes when it passes from a material to another, this is called "Refraction of light". This happens when there is a difference in the index of refraction between both mediums o materials. Therefore, that speed depends of <span>the medium through it passes.
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T<span>he index of refraction</span> is expressed as below:
n=c/v
"n" is <span>the index of refraction.
</span> "c" is <span>is the speed of light.
</span> "<span>v" is the phase velocity of light in the medium.
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A prism, a magnifying glass, a microscope, and eyeglasses refract light. Therefore, the correct option is: B) They refract light.
Potential Energy (PE) is found using the equation <em></em><em>mgh</em>, where
m = mass,
g = force of gravity,
h = height
Since we are using the metric system, our force due to gravity will be 9.8m/s^2. Plug in what we know, and we get
(1200kg)(45m)(9.8m/s^2)=PE
Multiply those three variables together, and you will get your potential energy, in Joules! Good luck!