1- A 5.0 µC charge is placed 2 m from a 2.5 µC charge. What is the potential ene
ID: 1416680 • Letter: 1
Question
1- A 5.0 µC charge is placed 2 m from a 2.5 µC charge. What is the potential energy of the system?
a) 0 . b) 56 mj . c) 14 mj . d) 8.2 mj
2- Two point charges +Q are a distance r apart. The potential at a point equidistant between the two charges on a line connecting the charges is ____.
a) 2kQ/r b) kQ/r c) 0 d) 4kQ/r
3- An isolated charged, conducting sphere of radius 15 cm has a surface charge density of 8.0 µC/m2. What is the potential on the surface of the sphere?
a) 0 ,b) 0.136mv ,c)18.8kv d,)120mv
Explanation / Answer
1) b) 56 mJ
U = k*q1*q2/d
= 9*10^9*5*10^-6*2.5*10^-6/2
= 0.05625 J
= 56.25 mJ
2) d) 4*k*Q/r
Potentail at equidistance, V = k*Q/(r/2) + k*Q/(r/2)
= 4*k*Q/r
3) b) 0.136 Mv
V = k*Q/r
= k*sigma*4*pi*r^2/r
= k*sigma*4*pi*r
= 9*10^9*8*10^-6*4*pi*0.15
= 0.136 Mv
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