\(\therefore \,\,dQ\, = \,\,(4\,\, - \,\,0.08t)\,dt\,\)
\(\,\therefore \,\,Q\,\, = \,\,\int\limits_0^{50} {(4\, - \,0.08t)} \,dt\,\,\, \)\(= \,\,\left[ {4t\,\, - \,\,\frac{{0.08{t^2}}}{2}} \right]_0^{50}\,\, = \,\,100\,\,C\)
હવે, \({\text{Q = ne}}\) પરથી \(n\,\, = \,\,\frac{Q}{e}\,\, = \,\,\frac{{100}}{{1.6\,\, \times \,\,{{10}^{ - 19}}}}\,\, = \,\,6.25\,\, \times \,\,{10^{20}}\)