Question

78. A spherical drop of radius 10-6m has ab-
sorbed 40 electrons. The energy required
to give an additional electron to it is
(i) 5.76 x 1024 ]
(ii) 9.21 x 10-21]
(iii) 3.4 x 10-18 ]
(iv) 2.4 x 10-20 j
8​

Answer 1

Explanation:

Energy=potential×charge

ie;E=V×q

V=k×Q/r. (k=9×10⁹Nm²/C²)

q=e

q=1.67×10^-19

eqn becomes: E=k(Q)q/r

given....Q=40e

E=k×40e×e/r

r=10^-6

=[9×10⁹×40×(1.67×10^-19)²>]÷10^-6 =9.2×10^-21J