Question

A dust particle has an excess charge of 4.0×106 electrons and a mass of 5.0×10−8g. It is initially held at d=1.0×10−3m directly above a fixed object of the same size that is charged with the same number of electrons. Both objects are in an evacuated container. A) Determine the maximum height of the dust particle after its release measured from its initial position. B) Determine the initial force exerted on the dust particle by the fixed charge.

Answer 1

The charge on the dust particle is (4x10 1.6x10 19 C) 6.4 x10-13 С Let the initial height be d and the final height beh+d. Apply the law of conservation of energy d (h+d) kq d h+d earrange the above equation.

kg mgd(h+d) kg mgd kg mgd Substitute the values in the above equation. kg mgd 9x10 N m/C) (64x1019 c) (5x10 kg) (9.81 m/s')(1x10 m) 7.515 x 10-3 m-1x10-3 m 1x10 m -6.515x10-3 m The inertial force acting on the dust particle by the fixed charge is,

kq2 mg 5x10" kg ) (9.81 m/s 1x10% m -368.64 x101 N-49.05x10-11 N -319.59 x10-1 N 1.7