question_answer

When a light of photons of energy 4.2 eV is incident on a metallic sphere of radius 10 cm and work function 2.4 eV, photoelectrons are emitted. The number of photoelectrons liberated before the emission is stopped, is \[1.25\times {{10}^{x}}\]. The value of x is ___. \[(e=1.6\times {{10}^{-19}}C\,\text{and}\frac{1}{4\pi {{\varepsilon }_{0}}}=9\times {{10}^{9}}N{{m}^{2}}{{C}^{-2}}\])

Answer:

8.0