Question

1. The Coulomb’s force between two charged particles q1 and q2, which are separated by a
distance d, is given by, F =
1
4πε0
q1q2
d2
.

a) Two protons in a molecule are 3.80 × 10−10m apart. Find the magnitude of the electric
force exerted by one proton on the other. [20 marks]
b) State how the magnitude of this force compares with the magnitude of the gravitational force
exerted by one proton on the other. [25 marks]
c) What must be a particle’s charge to mass ratio if the magnitude of the gravitational force
between two of these particles is equal to the magnitude of electric force between them?

Answer 1

Answer:

(a) $1.59$ × $10^{-9}$ N

(b) $1.3$ × $10^{36\\}$

Explanation:

(a) Charge of a proton = $+e$ = 1.6022 x$10^{-19}$ coulomb

Force= $k \frac{e^{2} }{r^{2} }$

K= Coulomb's Constant= 9×$10^{9}$ $kg-m^{3} s^{-2} C^{-2}$

substituting all the constant values,

F= $1.59$ × $10^{-9}$ N

(b) Gravitational Force, F= $G.\frac{mm'}{r^{2} }$

$\frac{F_{e} }{F_{g} }$ = $\frac{ke^{2} }{Gm^{2} }$ = $1.3$ × $10^{36\\}$