- #1
Tater
- 10
- 0
Homework Statement
A point charge Q is located at point P(0,-4,0) while a 10nc charge is uniformly distributed along a semicircular ring as shown in the figure. find the value of Q such that E(0,0,0)=0
Homework Equations
Q=ρLdl
dl = ρd∅ (because ρ and z are constant)
E=[itex]\frac{Qρ}{4piεr^2}[/itex]
The Attempt at a Solution
Okay so first I'd have to find Q using the formula above. I'd set my limits from 0 to pi.
Now looking at the formula for point charge, the only missing factor is R. I don't know how to express this. I know that the equation of a hemisphere is very similar to that of a circle. I came up with y=[itex]\sqrt{4-x^2}[/itex]. But now that I look at it, if I tried to convert that to polar using the relationships x=rcos[itex]\vartheta[/itex] and y=rsin[itex]\vartheta[/itex], it really seems wrong.
What's the best procedure in doing this? What should I say to myself every time I see a ring? Because to be honest, I really get confused when I see an odd figure labeled in terms of (x,y,z) even though it's much easier in another system.
Also, after finding R, I simply just stick to the formula and I will obtain my solution, right?
Thank you for any help :)