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Lolagoeslala
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Homework Statement
three point charges are located on a circular arc as shown:
a) find the electric potential at the centre of the arc (point P)
b) find the electric potential energy of a 25 pC point charge placed at P
Diagram: [ r= 4 cm = 0.04 m]
http://i1097.photobucket.com/albums/g356/wildpisces/Physics/23-p-023-alt.gif
The Attempt at a Solution
a) so i know the verticle components of the tension of Q1 and Q3 will cancel out therefore.
Q1 = (3 x 10^-9)(cos30)
Q1 = 2.598 x 10^-9 C
Q3 = (3 x 10^-9)(cos30)
Q3 = 2.598 x 10^-9 C
Q2 = -2 x 10^-9 C
Qtot= -2 x 10^-9 C + 2.598 x 10^-9 C + 2.598 x 10^-9 C
Qtot= 3.18 x 10^-9 C
Vp = KQtot/d
Vp = (9x10^-9 NM^2/c^2)(3.18 x 10^-9 C)/(0.04m)
Vp = 715.5 v
b) Eel = + K Qtot q / d
Eel = (9x10^-9 NM^2/c^2)(3.18 x 10^-9 C)(25x 10^12 C)/(0.04m)
Eel = + 17 nJ
so it will take 17 x 10^-9 to pull the P point?