Question

The charge on the electron is 1.6 x10-19 C. the number of electron need to be removed form a metal sphere of 0.05m radius so as to acquire a charge of 4 x10-5 C is a) 1.24 x104 b) 1.25 x103 c) 2.5 x103 d) 2.5 x104​

Answer 1

1.6 × 10^-19 C charge has 1 electron

So , 1 C charge has 1/(1.6× 10^-19) electron

= 6.25 × 10^18 electron

So 4 × 10^-5 C has 6.25× 10^18 × 4 × 10^-5

= 25 × 10^13

= 2.5 × 10^14 electron

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