Question

Two identical conducting spheres with negligible volume have 2.1 nC and -0.1 nC charges, respectively. They are brought into contact and then separated by a distance of 0.5 m. The electrostatic force acting between the spheres is ______ × 10^-9N.

[Given: 4πε₀ = `1/(9xx10^9)` SI unit]

Options

• 36

• 38

• 40

• 42

Answer 1

Two identical conducting spheres with negligible volume have 2.1 nC and -0.1 nC charges, respectively. They are brought into contact and then separated by a distance of 0.5 m. The electrostatic force acting between the spheres is 36 × 10^-9N.

Explanation:

When two spheres with charges of q'₁ = 2.1 nC and q'₂ = -0.1 nC are brought together and then separated by r = 0.5 m, then,

q'₁ = q'₂ `("Q"_1+"Q"_2)/2` = 1 nC

Between the two charged spheres, there is an electrostatic force.

F = `1/(4piepsilon_0).("q'"_1"q'"_2)/"r"_2`

= `9xx10^9xx(10^-9xx10^-9)/(0.5)^2`

= 36 × 10^-9N

∴ x = 36.