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Two point charges placed at a certain di...

Two point charges placed at a certain distance r in air exert a force F on each other. Then the distance r at which these charges will exert the same force in a medium of dielectric constnat K is given by

A

r

B

`r//k`

C

`r//sqrtk`

D

`rsqrtk`

Text Solution

Verified by Experts

The correct Answer is:
C
`F=1/(4piepsilon_0) .q^2/(r^2)`
`F.=1/(4piepsilon_0) .q^2/(k(r.)^2)`
`F =F. implies 1/r^2 =1/(k(r.)^2) implies (r.)/r = sqrt(1//k)implies r. =r/(sqrtk)`
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Knowledge Check

  • Two point charges placed at a distance r in air exert a force f on each other. The value of distance R at which they experience force 4F when placed in a medium of dielectric constant K = 16 is :

    A
    r
    B
    r/4
    C
    r/8
    D
    2r

  • Two point charges placed at a distance r in air experience a certain force. Then the distance at which they will experience the same force in a medium of dielectric constant K is

    A
    `r//K`
    B
    `Kr`
    C
    `(r )/(sqrt(K))`
    D
    `r+sqrt(K)`

  • The force of attraction between two charges at distance r, when the air is replaced by a medium of dielectric constant k.

    A
    Increases `k^(2)` times
    B
    decreases K times
    C
    remains uncharged
    D
    increases K times