Class 12 NEET Physics Moving Charges and Magnetism

Kinetic energy of a charged particle,

K=

1

2

mv2 or v=√

2K

m

Radius of the circular path of a charged particle in uniform magnetic field is given by
R=

mv

Bq

=

m

Bq

√

2K

m

=

√2mK

Bq

Mass of a proton,mp=m
Mass of an α-particle, mα=4m
Charge of a proton, qp=e
Charge of an α -particle,qα=2e
∴Rp=

√2mpKp

Bqp

=

√2mkp

Be

and Rα=

√2mαKα

Bqα

=

√2(4m)kα

B(2e)

=

√2mkα

Be

∴

Rp

Rα

=√

Kp

Kα

As Rp=Rα (Given)
∴Kα=Kp=1MeV