A neutral insulating sphere contains tightly bound electrons but can still polarize…
PHYSICS · Multi-part · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields
Problem
A neutral insulating sphere contains tightly bound electrons but can still polarize measurably. Within the sphere, equal and opposite charges of magnitude qind=2.5nC can be treated as if they are concentrated at two points separated by 1.5cm along a common diameter.
A point charge Q is placed on that same line outside the sphere so that the nearer induced charge is 6.0cm away from Q.
When the system reaches equilibrium, the measured magnitude of the attractive force on the sphere is 0.15N. Ignore all other forces.
(a) Write an expression for the net electrostatic force on the sphere in terms of Q, qind, and the two separations between Q and each induced charge. Clearly indicate which distance corresponds to which interaction.
(b) Using the numerical information given, calculate the magnitude of Q.
(c) Suppose the separation between the two induced charges inside the sphere could somehow be doubled while qind remained the same. Qualitatively describe how the magnitude of the attractive force would change, and support your answer with reasoning based on your expression from part (a).