Question

The force between two charges $8cm$ is apart is $6N$ . If each charge is moved towards the other by $1cm$ , then the force between them will become

• A. $5.50N$
• B. $10.6N$
• C. $16.5N$
• D. $22.00N$

Answer 1

The correct option is B $10.6N$

$r=8cm=8\times {10}^{-2}$

$F=6N$

Now, $F\propto \frac{1}{r^2}$

$F=\frac{k}{r^2}$ [k- propotionality constant]

$k=F{r}^2=6\times 8\times 8\times {10}^{-2}\times {10}^{-2}=0.0384$

$r^{\prime }\to r-2=6cm=6\times {10}^{-2}$

$F=\frac{k}{r^{\prime 2}}=\frac{0.0384}{6\times 6\times {10}^{-2}\times {10}^{-2}}=10.6N$