Question

Two point charges of +5 μC are so placed that they experience a force of 8.0 × 10⁻³N. They are then moved apart so that the force is now 2.0 × 10⁻³N. The distance between them is now

विकल्प

• `1/4` the previous distance

• double the previous distance

• four times the previous distance

• half the previous distance

Answer 1

double the previous distance

Explanation: 

`"F"_"coulomb" α 1/"r"^2`

`"F"_1/"F"_2="r"_2^2/"r"_1^2`

∴ `"r"_2^2/"r"_1^2=(8xx10^-3)/(2xx10^-3)`

∴ `"r"_2^2=4xx"r"_1^2`

∴ r₂ = 2r₁