An 100 eV electron is fired directly towards a large metal plate having surface charge density -2 10⁻⁶ Cm ⁻² . The distance from where the electron be projected, so that it just fails to strike the plate is

Step-by-step solution

Given that, initial kinetic energy of electrons, K_i=100 eV Initial potential energy, U_i=0 Let K_f and U_f be final kinetic and potential energies, K_f=0 By using law of conservation of energy, K_i+U_i=K_f+U_fU_f=K_i K_i=U_f= e d ₀ Now, substituting the values, we get 100 1.6 10⁻¹⁹= 1.6 10⁻¹⁹ d 2 10⁻⁶ 8.85 10⁻¹² d=0.44 10⁻³ ~m =0.44 ~mm