JEE Main 2024 Physics question
A particle of charge '–q' and mass 'm' moves in a circle of radius 'r' around an infinitely long line charge of linear charge density '+λ'. Then time period will be given as : (Consider k as Coulomb's constant)
Answer: (C)
Solution
The electrostatic force provides the centripetal force: mv²/r = qλ/(2πε₀r) = 2kλq/r. So v = √(2kλq/m) and T = 2πr/v = 2πr√(m/(2kλq)).