Two identical metal spheres have charges +15μC and +25μC areseparated by a distance. If the spheres are first brought into contact and then separated to the original distance, then the ratio of the new force to the previous force is 

Asked by mohammedmuhsin786786 | 1st Jul, 2021, 08:33: PM

Expert Answer:

Let q1 and q2 are the charges on sphere after they are made to get contact with each other.
 
When they are in contact , both spheres are at same potential.
 
Since both spheres are identical, and they are at same potential,  then q1 = q2
 
Since intial charges on spheres are 15 μC and 25 μC , by conservation of charge , we have
 
q1 + q2 = ( 15 + 25 ) μC = 40 μC 
 
Hence , we get , q1 = q2 = 20 μC .
 
If the distance between the charges are equal , mutual repulsion force is proportional to the
product of their charge magnitudes.
 
Hence ratio of new force to previous force  = ( 20 × 20 ) / ( 15 × 25 )  = 16/15

Answered by Thiyagarajan K | 1st Jul, 2021, 09:52: PM