A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5 × 103 N/C and points radially inward, what is the net charge on the sphere?

Question 1.21: A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5 × 10³ N/C and points radially inward, what is the net charge on the sphere?

Answer:

Method -1

Electric field intensity (E) at a distance (d) from the centre of a sphere containing net charge q is given by the relation,

 Where,

q = Net charge = 1.5 × 10³ N/C

d = Distance from the centre = 20 cm = 0.2 m ∈₀ = Permittivity of free space

     = 9 × 10⁹ N m² C⁻²

 = 6.67 × 10⁹ C = 6.67 nC

Therefore, the net charge on the sphere is 6.67 nC.

Method -2