Two point charges and are kept at a distance from each other in vacuum
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Two point charges q1 and q2 are kept at a distance r from each other in vacuum. Answer the following questions keeping the charges as point charges throughout.
(a) Write the mathematical statement of Coulomb’s law in scalar form and define every symbol used.
(b) If q1 is changed to mq1, q2 to nq2 and the separation to pr, obtain an expression for the ratio FF′, where F′ is the new force and F is the original force.
(c) Using your result in part (ii), explain how the electrostatic force can be doubled by changing (a) only one of the charges or (b) only the separation, keeping all other quantities the same. Support your explanation with suitable algebraic relations.