physics question related to electricity.

[ashwinkandel]

i m confused with one question.  hope someone posts the solution with reasoning. the question is uploaded here::
http://www.mediafire.com/?p02cor3wp44h9hj

[Chingoo]

6(a) Plate Y is positively charged, as weight acts in downward direction and a repulsive force of equal magnitude but opposite direction between the positively charged plate and positive particle causes the particle to be stationary.
6(b)(i) E = V/d (where E = Electric Field Strength, V = Potential Difference, d = Separation between Plates)
                   E = (630)/(0.75 x 10^-2)
                   E = 8.4 x 10⁴ NC^-1 or Vm^-1
6(b)(ii) F = ma (where F = Force Acting on the Particle, m = Mass of the Particle, a = Acceleration due to Gravity)
                   F = (9.6 x 10^-15)(9.81)
                   F = 9.418 x 10^-14 N ~ 9.42 x 10^-14 N
                   E = F/Q (where E = Electric Field Strength, F = Force Acting on the Particle, Q = Charge on the Particle)
                   Q = F/E
                   Q = (9.418 x 10^-14)/(8.4 x 10⁴)
                   Q = 1.121 x 10^-14 C ~ 1.12 x 10^-14 C

Feel free to ask for further explanation ^_^

[Deadly_king]

6(a) Plate Y is positively charged, as weight acts in downward direction and a repulsive force of equal magnitude but opposite direction between the positively charged plate and positive particle causes the particle to be stationary.
6(b)(i) E = V/d (where E = Electric Field Strength, V = Potential Difference, d = Separation between Plates)
                   E = (630)/(0.75 x 10^-2)
                   E = 8.4 x 10⁴ NC^-1 or Vm^-1
6(b)(ii) F = ma (where F = Force Acting on the Particle, m = Mass of the Particle, a = Acceleration due to Gravity)
                   F = (9.6 x 10^-15)(9.81)
                   F = 9.418 x 10^-14 N ~ 9.42 x 10^-14 N
                   E = F/Q (where E = Electric Field Strength, F = Force Acting on the Particle, Q = Charge on the Particle)
                   Q = F/E
                   Q = (9.418 x 10^-14)/(8.4 x 10⁴)
                   Q = 1.121 x 10^-14 C ~ 1.12 x 10^-14 C

Feel free to ask for further explanation ^_^

Nice piece of work Chingoo

Thanks for your help