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Two positive point charges Q and one neg...

Two positive point charges Q and one negative point charge q are arranged in a straight line in such a manner that the complete system remains in equilibrium. What can be the magnituude of Q/q ?

Text Solution

Verified by Experts

The correct Answer is:
4
Negative charge q must be there at the midpoint of two positive charges Q so that attraction of -q with Q may balance repulsion of other Q. Let 2r be the distance between positive charges Q then we can write the following equation.
`1/(4piepsilon_0)(qQ)/r^2=1/(4piepsilon_0)Q^2/(2r)^2`
`rArr q=Q/4 rArr` Q/q =4
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Knowledge Check

  • Two points charges +4 and +q are separated by distance r, where should a third point charge Q be placed that the whole system remains in equilibrium

    A
    `(2r)/(3)` from `q`
    B
    `(r )/( 3)` from `q`
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    D
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    B
    (b) `-Q/2`
    C
    (c) `Q/4`
    D
    (d) `-Q/4`

  • Two force point charges +q and +4q are a distance l apart. A third charge q_(1) is so placed that the entire system is in equilibrium. Find the location, magnitude and sign of the third charge.

    A
    `q_(1)=(4)/(9)q`
    B
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