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Electric field strength question help please watch

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    A +15 uC point charge Q1 is at a distance of 20 mm from a +10uC charge Q2.

    i) explain why there is a point along the line between the 2 charges at which the electric field strength is zero.

    ii) calculate the distance from this point to Q1 and to Q2.

    I've done i) but really stuck on ii). Managed to get very close to 0 for electric field strength and get answers for the distances through trial and error but don't know how to get the answer by setting up a mathematical equation.

    So far got 15uC/r1^2 = 10uC/r2^2 where r1 and r2 are the distances. Don't get how you can solve it when there are 2 unknowns please help
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    The distance between point charges is 20mm.

    Let the point at which E is zero be x mm away from Q1. Then the point is (20-x) mm from Q2
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    (Original post by Shaanv)
    The distance between point charges is 20mm.

    Let the point at which E is zero be x mm away from Q1. Then the point is (20-x) mm from Q2
    Wow I feel silly. Thank you!
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    (Original post by G.Y)
    Wow I feel silly. Thank you!
    We have all had those moments, dont sweat it.

    Did u draw a diagram by any chance, i feel like they always help
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    (Original post by Shaanv)
    We have all had those moments, dont sweat it.

    Did u draw a diagram by any chance, i feel like they always help
    I didn't but should do in future
 
 
 
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