This is not a homework assignment but a question from a past exam paper as i am studying for an exam on monday. I am one of only 3 out of 150 who have never done physics before this, the first year of an electronics degree. I would really appreciate any help.(adsbygoogle = window.adsbygoogle || []).push({});

1) A charge q1=1e-4C is in a fixed location at the origin r1=0. Calculate the energy required to transport a charge q2=2e-5C from infinity to the location r2=(0.1i + 0.2j)m

2) With q1 and q2 at the fixed locations r1 and r2, calculate the additional energy required to transport a third charge q3=1e-5C from infinity to the location r3=(0.2i + 0.1j)

V=(ke*Q)r

U=q(V1-V2)

I am very confused as to which values for Q i use in the equations and also what is the value for r if the point is at the origin, in fact having tried for almost three hours i am no closer to attaining an understanding.

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# Homework Help: Superposition principle and charges from infinity

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