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

a plastic ring of radius R = 50.4 cm. Two small charged beads are on the ring: Bead 1 of charge +2.00 μC is fixed in place at the left side; bead 2 of charge +6.00 μC can be moved along the ring. The two beads produce a net electric field of magnitude E at the center of the ring. At what (a) positive and (b) negative value of angle θ should bead 2 be positioned such that E = 2.22 × 105 N/C?

2. Relevant equations

Enety by -q2sinθ/4πε0R^2

Enetx by q1/4πε0R^2 - q2cosθ/4πε0R^2

3. The attempt at a solution

so i found enet of y and x by equations above then did E^2=(q1^2+q1^2-2q1q2cosθ/(4πε0R^2)^2

which simples to

θ=inverse cos [(q1^2+q1^2- (4πε0R^2)^2E^2)/(2q1q2)]

basically when i take the cos its a neg number and you can't take cos of neg number so i am confused what i am doing wrong bc my professor said method was correct

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# Homework Help: Electric field of a ring and beads

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