A conductor of capacity 4 units, charged with 100 units of positive charge is connected to another conductor of capacity 2 units, charged with 20 units of negative charge. What is the change in potential of each conductor ? What will be the charges of each of them after connection?

Explanation

Capacity of the first conductor, `C_=4` units, charge, `Q_1 =100` units.
Potential, `V_1= (Q_1)/(C_1)= (100)/(4)=25` units
Capacity of the second conductor, `C_2=2` units, charge, `Q_2= -20` units.
Potential, `V_2= (Q_2)/(C_2) = (-20)/(2)= -10` units.
After connection, suppose, the common potential of the two conductors becomes equal to V.
`:. " " V= (Q_1+Q_2)/(C_1+C_2)= (100-20)/(4+2)= (80)/(6)=(40)/(3)= 13.33` units
So, the change of potential of first conductor
`= 25 - 13.33 = 11.67` units
The change of potential of second conductor
`= 13.33 -(-10) = 23.33` units
Residual charge in the first conductor after connection,
`q_1= C_1V = 4xx(40)/(3)= 53.33` units
Residual charge in the second conductor after connection,
`q_2 = C_2V = 2xx (40)/(3) = 26.67` units.