Question

A charged cloud system produces an electric field in the air near earth's surface. a particle of charge -2.0 × 10-9 c is acted on by a downward electrostatic force of 4.3 × 10-6 n when placed in this field. (a) what is the magnitude of the electric field? (b) what is the magnitude of the electrostatic force on a proton placed in this field? (c) what is the gravitational force on the proton? (d) what is the ratio of the electrostatic force to the gravitational force in this case?

Answer 1

Part a)

Magnitude of electric field is given by force per unit charge

$E = \frac{F}{q}$

$E = \frac{4.3 * 10^{-6}}{2 * 10^{-9}}$

$E = 2150 N/C$

Part b)

Electrostatic force on the proton is given as

F = qE

$F = 1.6 * 10^{-19} * 2150$

$F = 3.44 * 10^{-16} N$

PART C)

Gravitational force is given by

$F_g = mg$

$F_g = 1.6 * 10^{-27}*9.8$

$F_g = 1.57 * 10^{-26} N$

PART d)

Ratio of electric force to weight

$\frac{F_e}{F_g} = \frac{3.44 * 10^{-16}}{1.57*10^{-26}}$

$\frac{F_e}{F_g} = 2.2 * 10^{10}$