What is an Atwood Machine?
1 answer:
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Answer:
at the beginning:
when the plates are pulled apart:
Explanation:
The capacitance of a parallel-plate capacitor is given by
where
k is the relative permittivity of the medium (for air, k=1, so we can omit it)
is the permittivity of free space
A is the area of the plates of the capacitor
d is the separation between the plates
In this problem, we have:
is the area of the plates
is the separation between the plates at the beginning
Substituting into the formula, we find
Later, the plates are pulled apart to , so the capacitance becomes
Answer:
It can occur only when light is incident on an interface where the index of refraction on the other side is less.
Explanation:
When the light passes from a denser medium, with refractive index n1, to another less dense medium, with refractive index n2, the incident light beam is refracted in such a way that it is not able to cross the surface between both media, the light beam is fully reflected and completely confining in the optically denser medium through which it propagates. For this phenomenon to occur, it is necessary that the angle of the incident light beam with respect to the normal be greater than or equal to the critical incidence angle θc. The critical angle can be calculated as :