What is photo-electric emission

When light falls upon certain metals, they emit electrons. these emitted electrons are called photo-electrons and the process of emitting these electrons is known as photo-electric emission. the enrgy within the light helps the elctrons of the metal to gain more energy and then get emitted from the surface of the metal. The light falling on the surface of the metal gets absorbed and helps in the release of the electrons.Most of the Alkali metals are highly sensitive to light energy and it readily discharges electron by this method.

Distance^2= yellow line ^2 (see picture) = 30^2 + 49^2so distance = squareroot of (300^2 +49^2)i dont know if this is how to solve it, but i cnt think of another way

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