Question

1.Two identical spheres carrying charges - 9 uC and 5 uC respectively are kept in contact and then separated from each other. Point out true statement from the following. In each sphere
1) 1.25 x 10"' electrons are in deficit
2) 1.25 x 10" electrons are in excess
3) 2.15 x 10" electrons are in excess
4) 2.15 x 1013 electrons are in deficit​

Answer 1

Given,

Two identical spheres carrying charges -9μC and 5μC respectively are kept in contact and then seperated from each other.

To find,

final charge on each of sphere, Q = (-9μC + 5μC)/2 = -2μC

[ negative sign indicates that charge on each sphere are in excess ]

so number of electrons are in excess = magnitude of charge on each sphere/charge on each electron

= 2μC/1.6 × 10^-19 C

= (2 × 10^-6)/(1.6 × 10^-19)

= 1.25 × 10¹³

Therefore 1.25 × 10¹³ electrons are in excess. option (2) is correct choice.