(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Charged Wire laid out in a semicircle, test charge at the center of the "Circle"

what is the charge of dQ. This isn't my whole question but is the bit of it that I cant understand the actual question asks you to go the whole nine yards with calculating the force on the test charge

3. The attempt at a solution

Charge density: [tex] \frac{total charge}{length of tiny wire piece}=\frac{Q}{\frac{2\pi R}{2}} = \frac{Q}{\pi R} [/tex]

so charge of wire chunk = [itex] \frac{Q}{\pi R} * d\theta [/itex]

when my solution manual uses the charge of the wire chunk it uses [itex] \frac{Q}{\pi R} * d\theta * R [/itex]

I can't figure out why, any hints?

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# Semicircular charged wire question

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