Question

A. An electrostatic paint sprayer has a  0.17 m-diameter metal sphere at a potential of 25.0 kV that repels paint droplets onto a grounded object. What charge must a 0.1 µg drop of paint have to arrive at the grounded object (at 0 volts) with a speed of 12 m/s? Assume the paint drop is initially at the surface of the metal sphere with zero velocity. You may ignore gravitational potential energy (but not electric potential energy!).

B. Two-point charges are on the ?y axis. One charge of 3.18 NC is at the origin and the second charge of 6.35 NC is at the point ?=29.2y=29.2 cm. Calculate the electric potential at y=6.96 cm.

Answer 1

In this case, the potential energy (9V) is transferred to kinetic energy to move the drop 1 mv =gV 2 Rearrange the equation my2 q= 21 Substitute the numerical values (0.1x100 g)(12 m/s) 225x10 v) = 2.88x10-10 = Expression for electric potential: V = For system of two charges koko + ?1 - + V=k ?1 here, 11 = 6.96 cm -0 cm = 6.96 cm r2 = 29.2 cm -6.96 cm = 22.24 cm; therefore 3.18x10°C 6.35 x10° C 6.96 X10-2 m 22.24 x 10-2 m = 668.17 V V ={9x10°) + If round off the result to 2 significant digits V = 668 V