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.
The heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.
Explanation:
The heat energy required to convert a substance or to heat up or increase the temperature of a substance can be obtained from the specific heat formula.
As per this formula, the heat energy applied should be equal to the product of mass of the substance with temperature gradient and also with specific heat of the substance. Basically, the heat provided to increase or convert a substance should be more than the specific heat of the substance.

Since, here the mass of the substance X is given as m = 20g and the temperature change is given from -10°C to 70°C.
Then ΔT = (70-(-10))=70+10=80°C.
As the substance is unknown, the specific heat of that substance can also not be determined. Hence keep it as C.

Q = 1600C J
Thus, the heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.
Yes you should if you will like to. It is your opinion so follow your dreams if they are your dreams.
Answer: Well there is a simple solution which is death..