The magnitude of the magnetic field on which an electron accelerated from rest through a voltage of 770v enters a region of constant magnetic field is 3.744 *
T
From the conservation of energy, we have



=
m/s
At Equilibrium, Centripetal force = magnetic force

B=mv/rq
by putting, m=9.11* 10^-31 kg
v=1.664*10^7m/s
r=25*10^-2m
q=1.6*10^-19 C
We get, B=3.774* 10^-4 T
Hence the magnitude of the magnetic field, B=3.774* 10^-4 T
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