Question

cs
3. A proton and an alpha particle both enter a
region of uniform magnetic field B, moving
at right angles to the field B. If the radius of
circular orbits for both the particles is equal
and the kinetic energy acquired by proton is
1 MeV, the energy acquired by the alpha
particle will be
(a) 4 MeV
(b) 0.5 MeV
(C) 1.5 MeV
(d) 1 MeV
​

Answer 1

Answer:

The radius of circular path is r=

qB

2mE

So,

r

p

r

α

=

m

p

E

p

m

α

E

α

q

α

q

p

or, 1=

E

p

E

α

as radius of both particles are equal and the mass of alpha particle is 4 times of proton and charge is 2 times of proton.

Thus, E

α

=E

p

=1MeV

Answer 2

Answer:

The radius of circular path is r=

qB

2mE

So,

r

p

r

α

=

m

p

E

p

m

α

E

α

q

α

q

p

or, 1=

E

p

E

α

as radius of both particles are equal and the mass of alpha particle is 4 times of proton and charge is 2 times of proton.

Thus, E

α

=E

p

=1MeV