A question concerning electric field
This question appeared in 1986 al physics mc paper:Given:permittivity of free space = 8.85 x 10^-12 F/m. A conducting sphere of radius 0.1m carries a positive charge of 10^-4C. A particle P of mass 2 x 10^-5 kg carrying a negative charge of 10^-10C is released from rest at a distance of 1m from thecentre of the sphere. If the force due to gravity is neglected, the velocity of P when it strikes the surface of the shpere will be
A. 2.8m/s B. 9.0m/s C. 29.8m/s D. 81.0m/s E. 890m/s
The answer is B, while I found is A. What's wrong? ke = epe
1/2 mv^2 = Qq/4epi (1/R-1/r)
r is distance of charge from center of sphere
R is radius of sphere how do you find A??
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