AP EAMCET201825 Apr 2018Morning ShiftPhysicsElectrostaticsActual
Two equally charged metal spheres A and B repel each other with a force of 4 × 10 - 5 N . Another identical uncharged sphere C is touched to A and then placed at the mid point of the line joining the spheres A and B . The net electric force on the sphere C is
Options
- A4 × 10 - 5   N from C to A
- B4 × 10 - 5   N from C to B
- C8 × 10 - 5   N from C to A
- D8 × 10 - 5   N from C to B
Correct answer
A. 4 × 10 - 5   N from C to A
Step-by-step solution
Let us suppose that charge on both spheres is, q and when it touches with the uncharged sphere then charge distributed in order of q 2 each A   &   B , Before- F = K q 2 r 2 = 4 × 10 - 5   N after- F A C = K q 4 2 r 4 2 = K q 2 r 2   &   F B C = K q 2 2 r 4 2 = K 2 q 2 r 2 F C = F B C - F A C = K q 2 r 2   = 4 × 10 - 5   N From C to A