When visible light, X rays, gamma rays, or other forms of electromagnetic radiation are shined on certain kinds of matter, electrons are ejected. That phenomenon is known as the photoelectric effect. The photoelectric effect was discovered by German physicist Heinrich Hertz (1857–1894) in 1887. You can imagine the effect as follows: Suppose that a metal plate is attached by two wires to a galvanometer. (A galvanometer is an instrument for measuring the flow of electric current.) If light of the correct color is shined on the metal plate, the galvanometer may register a current. That reading indicates that electrons have been ejected from the metal plate. Those electrons then flow through the external wires and the galvanometer. HOPE THIS HELPED
Regardless of the source's mobility, light travels at the same speed.
<h3>What makes special relativity so crucial?</h3>
In the calculating and interpretation of high-velocity phenomena, as well as on our methods of thinking, Einstein's special relativity has had a significant influence on the area of physics. Today, we have a considerably better knowledge of space and time than we did at the start of the century.
<h3>Why is special relativity thus named?</h3>
Because it exclusively uses inertial frames to apply the concept of relativity, the theory is known as "special". General relativity, which Einstein created, applies the principle broadly, that is, to any frame, and this theory takes the gravitational forces into account.
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Answer : The static friction depends on two factors
1. Roughness of the surface
2. Force
Explanation : Friction occur when surface is not smooth.
The formula of friction is

Static friction depends on the roughness of the surface and force which is trying to push to object along the surface.
Static friction is caused by the attraction between two surfaces that are in contact. when the surface will rough and the object will heavier then the force will be larger.
While falling, both the sheet of paper and the paper ball experience air resistance. But the surface area of the sheet is much more than that of the spherical ball. And air resistance varies directly with surface area. Hence the sheet experiences more air resistance than the ball and it falls more slowly than the paper ball.
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