Question

Two similar very small conducting spheres having charges 40 mC and – 20 mC are some distance apart. Now they are touched and kept at same distance. The ratio of the initial to the final force between them is

• A. 8 : 1
• B. 4 : 1
• C. 1 : 8
• D. 1 : 1

Answer 1

Answer: (A)

8 : 1

Answer 2

F_i = ,

40 – 20 = 2q Ž q = 10 mC

F_f = $\frac { k ( 10 ) ( 10 ) } { r ^ { 2 } }$

= $\frac { 40 \times 20 } { 10 \times 10 }$ = $\frac { 8 } { 1 }$= 8 : 1