Advertisements
Advertisements
Question
Explain experimentally observed facts of the photoelectric effect with the help of Einstein’s explanation.
Advertisements
Solution
Explanation for the photoelectric effect:
The experimentally observed facts of the photoelectric effect can be explained with the help of Einstein’s photoelectric equation.
-
As each incident photon liberates one electron, then the increase of intensity of the light (the number of photons per unit area per unit time) increases the number of electrons emitted thereby increasing the photocurrent. The same has been experimentally observed.
-
From Kmax = hv – Φ0, it is evident that Kmax is proportional to the frequency of the light and is independent of the intensity of the light.
-
As given in Einstein’s photoelectric equation, there must be minimum energy (equal to the work function of the metal) for incident photons to liberate electrons from the metal surface. Below which, emission of electrons is not possible. Correspondingly, there exists a minimum frequency called threshold frequency below which there is no photoelectric emission.
-
According to the quantum concept, the transfer of photon energy to the electrons is instantaneous so that there is no time lag between the incidence of photons and the ejection of electrons.
APPEARS IN
RELATED QUESTIONS
A light source of wavelength 520 nm emits 1.04 × 1015 photons per second while the second source of 460 nm produces 1.38 × 1015 photons per second. Then the ratio of power of second source to that of first source is
Photons of wavelength λ are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of radius R by a perpendicular magnetic field having magnitude B. The work function of the metal is
Give the definition of intensity of light according to quantum concept and its unit.
How will you define threshold frequency?
Define stopping potential.
Obtain Einstein’s photoelectric equation with the necessary explanation.
Give the construction and working of photo emissive cell.
How many photons per second emanate from a 50 mW laser of 640 nm?
A 3310 Å photon liberates an electron from a material with energy 3 × 10−19 J while another 5000 Å photon ejects an electron with energy 0.972 × 10−19 J from the same material. Determine the value of Planck’s constant and the threshold wavelength of the material.
At the given point of time, the earth receives energy from the sun at 4 cal cm–2 min–1. Determine the number of photons received on the surface of the Earth per cm2 per minute. (Given: Mean wavelength of sunlight = 5500 Å)
