Q.

A particle of charge ‘−q’ and mass ‘m’ moves in a circle of radius ‘r’ around an infinitely long line charge of linear density ‘+λ’. Then time period will be given as

(Consider k as Coulomb’s constant)        [2024]

1 T2=4π2m2kλqr3  
2 T=2πrm2kλq  
3 T=12πrm2kλq  
4 T=12π2kλqm  

Ans.

(2)

Fe=mv2rqE=mv2r

q(2Kλr)=mv2rv=2Kqλm

T=2πrv=2πr2Kqλm=2πrm2Kqλ