Question

Assertion: Kinetic energy of photoelectrons emitted by a photosensitive surface depends upon the intensity of the incident photon.
Reason: The ejection of electrons from metallic surfaces is possible with frequency of incident photon below the threshold frequency.
A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is false but R is true
D. A and R are false

Answer 1

Hint: Here we are going to consider the results of a photoelectric effect experiment to answer this question. Photoelectric effect is the emission of photoelectrons from a metal surface as a result of absorbing light When Heinrich Hertz demonstrated the photoelectric effect in 1887, he helped launch the field of quantum mechanics.

Complete step by step solution:
Albert Einstein explained the photoelectric effect in 1905, and was awarded the Nobel Prize in physics for his work in 1921. Einstein's explanation of the photoelectric effect is that light is composed of packets of energy called photons. Photons possess sufficient energy to eject an electron from a metal surface.

The minimum frequency i.e, required to eject an electron is called the threshold frequency. The higher the intensity of the light, the more photons it contains, and the more electrons are ejected. Kinetic energy of electrons is dependent on the frequency of incident radiation.

The threshold frequency is determined by the metal's properties. The higher the threshold frequency, the more sensitive the metal is to light. The energy required to extract an electron from a metal is called the work function. The ejection of electrons from the metal surface is possible if the frequency of incident radiation is greater than the threshold frequency.

The photoelectric effect has a number of applications. Photovoltaic cells use the photoelectric effect to convert light into electricity. Photoelectric cells are used in solar panels and light detectors. From the discussion we conclude that both assertion and reason are false.

Therefore, option D is the correct answer.

Notes: In 1905, Albert Einstein explained the photoelectric effect using his theory of relativity. Einstein showed that light is composed of packets of energy called photons. When a photon hits a metal surface, it transfers its energy to an electron, which is then ejected from the surface. The higher the intensity of the light, the more photons it contains, and the more electrons are ejected.