Question

2. Two equal metal balls are charged to 10 and -20 units of electricity. Then they are brought in contact with each other and then again separated to the original distance. The ratio of magnitudes of the force between the two balls before and after contact is a) 8:1 b) 1:8 c) 2:1 d) 1:2

Answer 1

Answer:

Option C

Explanation:

Electric charges do attract or repel each other and with some force.

This force of the attraction or repulsion between two charged bodies can be measured through Coulomb's law:

F = kq1q2/r2

where q1 and q2 are the two points charges

In our case;

q1 = 10

q2 = -20

Hence F would be

F(before) = -200k/r2

Now when they meet each other, 10 charge is nuetarilised by -20 charge, leaving behind only -10 charge

F(after) = -10k/r2

Ratio of force before and after contact = -200k/r2 / -10k/r2 = 2:1