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The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is made on and a saturation photocurrent is recorded. An electric field is switched on which has a vertically downward direction.
(A) The photocurrent will increase
(B) The kinetic energy of the electrons will increase
(C) The stopping potential will decrease
(D) The threshold wavelength will increase

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Last updated date: 16th May 2024
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Answer
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Hint We know that photoelectric effect, phenomenon in which electrically charged particles are released from or within a material when it absorbs electromagnetic radiation. The effect is often defined as the ejection of electrons from a metal plate when light falls on it. Since light is bundled up into photons, Einstein theorized that when a photon falls on the surface of a metal, the entire photon's energy is transferred to the electron. A part of this energy is used to remove the electron from the metal atom's grasp and the rest is given to the ejected electron as kinetic energy.

Complete step by step answer
We know that the electric field is defined as the electric force per unit charge. The direction of the field is taken to be the direction of the force it would exert on a positive test charge. The electric field is radially outward from a positive charge and radially in toward a negative point charge.
At the same time, we can conclude that the space around an electric charge in which its influence can be felt is known as the electric field. The electric field Intensity at a point is the force experienced by a unit positive charge placed at that point. Electric Field Intensity is a vector quantity.
Force on an electron in an electric field is given by:
$\mathrm{F}=\mathrm{e} \mathrm{E}$
We can say that kinetic energy is the energy of mass in motion. The kinetic energy of an object is the energy it has because of its motion. Solid particles have the least amount of energy, and gas particles have the greatest amount of energy. The temperature of a substance is a measure of the average kinetic energy of the particles. A change in phase may occur when the energy of the particles is changed.
So, if an electric field is switched on which has a vertically downward direction then the kinetic energy of the electrons will increase and will reach the collector plate in an experiment on photoelectric effect that is kept vertically above the emitter plate.

So, the answer is option (B).

Note We can conclude that study of the photoelectric effect led to important steps in understanding the quantum nature of light and electrons and influenced the formation of the concept of wave-particle duality. The photoelectric effect is also widely used to investigate electron energy levels in matter.
On the other hand, the inverse photoelectric effect is the opposite to the photoelectric effect. In this case electrons absorbed by the atom cause the emission of photons. Relation between electron's kinetic energy and light frequency.