CONCEPT: [ alt="F1 J.K 3.8.20 Pallavi D6" src="//storage.googleapis.com/tb-img/production/20/08/F1_J.K_3.8.20_Pallavi_D6.png" style="width: 363px; height: 274px;"> Photoelectric effect: When the light of a sufficiently small wavelength is incident on the metal surface, electrons are ejected from the metal instantly. This phenomenon is called the photoelectric effect. Stopping potential: It is defined as the potential required to stop the ejection of an electron from a metal surface when the incident beam of energy is greater than the work function of the metal. Work function: It is the minimum amount of energy required so that metal emits an electron. It is represented by ϕ. Einstein’s equation of photoelectric equation: ⇒ KEmax = E - ϕo Where E = incident energy of photons, ϕo = work function, and KE = maximum kinetic energy of electrons. Calculation: Case 1: When 5eV is incident 5eV = W + 2eV W = 3eV Case 2: When 6eV is incident 6 = 3 + K.E K.E = 3 eV To stop the electron, a negative potential is required whose magnitude is the equivalent voltage is (3V) Hence stopping potential = -3V