Answer:
d. 16
Step-by-step explanation:
Let
Charge on particle=q and mass of particle=m
Radius=2r
Magnetic field=2B
We have to find by what factor the maximum kinetic energy of particle increases.
We know that
Maximum kinetic energy of particle is given by

Substitute the values then we get
Maximum kinetic energy of particle =

Maximum kinetic energy of particle =

Hence, the maximum kinetic energy of particle increase by 16 when radius is twice and magnetic field is twice strong.
Answer:d.1 6