A particle of mass m carrying charge q1 is revolving around a fixed ch...
For the particle to move in a perfect circle, the centripetal force acting on the particle must be equal to the electrostatic attractive force due to the charge placed at center.
A particle of mass m carrying charge q1 is revolving around a fixed ch...
Solution:
Given:
Mass of the particle, m
Charge on the particle, q1
Fixed charge, -q2
Radius of the circular path, r
To find:
Period of revolution, T
Speed of the particle, v
Formula used:
Coulomb's law states that the force between two charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
F = k(q1*q2)/r^2
where,
k = Coulomb's constant = 9 x 10^9 Nm^2/C^2
q1 and q2 are the charges
r is the distance between the charges
Centripetal force is given by:
Fc = mv^2/r
where,
m is the mass of the particle
v is the speed of the particle
r is the radius of the circular path
Equating the two forces, we get:
k(q1*q2)/r^2 = mv^2/r
Simplifying the above equation, we get:
v = sqrt(k*q1*q2/mr)
Period of revolution is given by:
T = 2πr/v
Substituting the value of v in the above equation, we get:
T = 2πmr/sqrt(k*q1*q2)
Calculation:
Given,
m = 2 x 10^-3 kg
q1 = 3 x 10^-6 C
q2 = -2 x 10^-6 C
r = 0.1 m
Using the formula v = sqrt(k*q1*q2/mr), we get:
v = sqrt(9 x 10^9 * 3 x 10^-6 * -2 x 10^-6 / 2 x 10^-3 * 0.1) = 3 x 10^3 m/s
Using the formula T = 2πmr/sqrt(k*q1*q2), we get:
T = 2π * 2 x 10^-3 * 0.1 / sqrt(9 x 10^9 * 3 x 10^-6 * -2 x 10^-6) = 0.14 s
Therefore, the period of revolution is 0.14 s and the speed of the particle is 3 x 10^3 m/s.