A charged particle is suspended in equilibrium in a uniform vertical electric field of intensity 20000V/m . If mass of the particle is 9.6×10−16kg , the charge on it and excess number of electrons on the particle are respectively (g=10m/s2) :
Charge on the particle is given by
qE=mg or q=Emg=200009.6×10−16×10=4.8×10−19
When there is an excess of n electrons on the particle, then
q=ne
So, n=eq=1.6×10−194.8×10−19=3