The distance between two negatively charged dust particle is 1 mm and they repel ech other with a force of 4.0*10^-5 N.If the charge on one particle is 4 times that of other,then find the no of electron charging them seperately.The charge on electron is (5/3)*10^-19C.
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r = 1 mm = 1*10^-3 m
F = 3.0*10^-5N
k = 9 * 10^9
q1 = ?
q2 = 4*q1
F = k*q1*q2/r^2
3*10^-5 = 9*10^9*4q1^2 / (1*10^-3)^2
4q1^2 = 3.3333*10^-21
q1^2 = 8.333*10^-22
q1 = sqrt(8.333*10^-22
q1 = 2.887*10^-11
1 electron has a charge of 5/3 * 10^-19 c
x electron = 2.887*10^-11
x = 2.887*10^-11 / (5/3)*10^-19 = 1.73 * 10^8 electrons
q1 = 1.73 * 10^8 electrons
q2 = 4q1 = 6.93 * 10^8 electrons.
F = 3.0*10^-5N
k = 9 * 10^9
q1 = ?
q2 = 4*q1
F = k*q1*q2/r^2
3*10^-5 = 9*10^9*4q1^2 / (1*10^-3)^2
4q1^2 = 3.3333*10^-21
q1^2 = 8.333*10^-22
q1 = sqrt(8.333*10^-22
q1 = 2.887*10^-11
1 electron has a charge of 5/3 * 10^-19 c
x electron = 2.887*10^-11
x = 2.887*10^-11 / (5/3)*10^-19 = 1.73 * 10^8 electrons
q1 = 1.73 * 10^8 electrons
q2 = 4q1 = 6.93 * 10^8 electrons.