The electrostatic force on a small sphere of charge 0.4 µC due to ano

1.	The electrostatic force on a small sphere of charge 0.4 µC due to another small sphere of charge –0.8 µC in the air is 0.2 N.(a) What is the distance between the two spheres?(b) What is the force on the second sphere due to the first?
Answer» (a) Given, The charge on 1^st sphere (q₁) and 2^nd sphere (q₂) is 0.4 µC or 0.4 × 10^-6C and -0.8 × 10^-6C respectively. The electrostatic force on the 1^st sphere is given by F = 0.2N. Electrostatic force between the spheres is given by the relation : F = 1/4πϵo * q1q2/r² Here, ϵ_o= permittivity of free space and, 1/4πϵ_o= 9 × 10⁹ Nm²C^-2 r² = 1/4πϵ_o* q1q2/F = 0.410^-6810^-6910⁹ / 0.2 = 14410^-4 r = √144 x 10^-4 = 12 x 10^-2 = 0.12m Therefore, the distance between the two spheres = 0.12 m (b) Since the spheres have opposite charges, the force on the second sphere due to the first sphere will also be equal to 0.2N.

The electrostatic force on a small sphere of charge 0.4 µC due to another small sphere of charge –0.8 µC in the air is 0.2 N.(a) What is the distance between the two spheres?(b) What is the force on the second sphere due to the first?

Answer»

(a) Given,

The charge on 1^st sphere (q₁) and 2^nd sphere (q₂) is 0.4 µC or 0.4 × 10^-6C and -0.8 × 10^-6C respectively.

The electrostatic force on the 1^st sphere is given by F = 0.2N.

Electrostatic force between the spheres is given by the relation :

F = 1/4πϵo * q1q2/r²

Here,

ϵ_o= permittivity of free space and,

1/4πϵ_o= 9 × 10⁹ Nm²C^-2

r² = 1/4πϵ_o* q1q2/F

= 0.4*10^-6*8*10^-6*9*10⁹ / 0.2 = 144*10^-4

r = √144 x 10^-4 = 12 x 10^-2 = 0.12m

Therefore, the distance between the two spheres = 0.12 m

(b) Since the spheres have opposite charges, the force on the second sphere due to the first sphere will also be equal to 0.2N.