During an intense thunderstorm a thundercloud may be modelled as a uniformly charged…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential
Problem
During an intense thunderstorm a thundercloud may be modelled as a uniformly charged sphere of radius 400m carrying a total charge of −40C. The ground beneath the cloud can be approximated as a point charge of +40C located 600m below the cloud’s centre.
Using this model, answer the following:
(a) Explain, on the basis of conservation of charge, why the cloud and the ground are expected to possess equal and opposite charges before a lightning discharge occurs.
(b) Treating both the cloud and the ground as point charges, calculate the magnitude of the electrostatic force between them.
(c) An ionised water droplet of mass 3.0×10−5kg carrying a charge of +2.4×10−14C is located midway between the two point charges. Determine whether the droplet will accelerate upwards toward the cloud or downwards toward the ground, showing your calculations clearly.
(d) If the magnitude of the charge on the cloud were suddenly doubled while the separation remained the same, predict qualitatively how this would affect the probability of a lightning strike. Give reasons for your answer.