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A question about Coloumb's law (mostly maths related dealing with ratios). Watch

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    Can you please help me?

    The force between two particles r away from each other of charge Q, is F. What is the electrostatic force they exert on each other when Q becomes root Q and r becomes root r?

    Thank you for reading, and if so, for responding.
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    Well, Coulomb's law states:

    F = k \frac{Q_1 Q_2}{r^2}

    In your scenario, you've been told:

    Q_1 = \sqrt{Q}
    Q_2 = \sqrt{Q}
     r = \sqrt{r}

    Plug those into Coloumb's law.
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    I get F becomes root F, as root Q x itself = Q and root r x itself is also r, so it is Q/r which is root of QQ/r^2, yet the answer apparently is F.
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    (Original post by BrainJuice)
    I get F becomes root F, as root Q x itself = Q and root r x itself is also r, so it is Q/r which is root of QQ/r^2, yet the answer apparently is F.
    I don't get F as an answer, but I don't quite get get root F either. You need to remember there's the value 'k' in there.

    If the answer is supposed to be just 'F', I suspect the question is more about how the equation for the force doesn't change. No matter if Q is a million times larger and r a million times smaller or whatever, the Coulomb equation is always F = k \frac{Q_1 Q_2}{r^2}, but this seems a bit trivial.

    I take it this is an A-level physics question of some kind? I always detested the A-level physics syllabus, and the way the whole course content is approached in all the books.
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    (Original post by Pessimisterious)
    I don't get F as an answer, but I don't quite get get root F either. You need to remember there's the value 'k' in there...
    Yeah it is, the question first states that for two point charges both of equal charge Q, speration r, the force is F. It then tries to get me to derive in terms of F what the force will be in the cases I mentioned above. Sorta like if Q was the only thing that changed and it became twice the amount for both charges, then F would be 4F as F is directly proportional to Qq.

    Thank you for helping though.
 
 
 
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