Question

Two point charges of +3 micro column and +4 micro column repel each other with force of10 newton if each is given an additional charge -6 micro column, the new force is

Answer 1

AnswEr :

The new force is 5 N

Explanation :

• The charges + 3uC and + 4uC are given an additional - 6uC each

• Initial Coulombic Force (F) = 10 N

The charges eventually become - 3uC and - 2uC

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From Coulomb's Inverse Square Law,

$\sf \: 10 = \dfrac{K (3 \times {10}^{ - 6} )(4 \times {10}^{ - 6} ) }{{ r}^{2} } - - - - - - - - (1)$

Let the new force be F'

$\sf \: F' = \dfrac{K( - 3 \times {10}^{ - 6} ) ( - 2 \times {10}^{ - 6}) }{ {r}^{2} } - - - - - -(2)$

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Dividing equations (1) and (2),

$\implies \sf \dfrac{10}{F'} = \dfrac{3 \times 4 \times {10}^{ - 12} }{ 2 \times \: 3 \times {10}^{ - 12} } \: \times \: \cancel{ \dfrac{Kr^2}{Kr^2}} \\ \\ \implies \sf \dfrac{10}{F'} = \dfrac{12}{6} \\ \\ \implies \sf 12F' = 60 \\ \\ \large{ \implies \: \boxed{ \boxed{ \sf F' = 5 \: N}}}$

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