Class-12th Physics, CBSE and UP Board
Electric Charges and Fields,
Chapter-1, Exercise -1, Q-1.1
NCERT Solutions for Class 12th Physics
What is the force between two small charged spheres having charges of 2 × 10⁻⁷ C and 3 × 10 ⁻⁷ C placed 30 cm apart in air?
Share
Since force between two charges q1 and q2 separated by a distance of r is given by expression:
F=1 /4πε0 x q1q2/r²
Where ε0 =Permittivity of free space and value of
1 /4πε0 =9 X 109 Nm 2C⁻²
and given
Charge on the first sphere, q1= 2 x 10-7 C Charge on the second sphere,
q2= 3 x 10-7 C Distance between the spheres, r = 30 cm = 0.3 m
Therefore
F=9 x 109 x (2 x 10-7 x3 x 10-7 )/(0.3 )²
F=6 X 10⁻ ³ N
Hence, force between the two small charged spheres is 6 x 10-3 N. The charges are of same nature. Hence, force between them will be repulsive.