Answer:
KE = 160.41 keV
Step-by-step explanation:
given data
radii = 1.00 cm
radii = 2.40 cm
uniform magnetic field of magnitude = 0.0540 T
to find out
energy (in keV) of the incident electron
solution
first we find the velocity of charge with radii 1 cm then 2.40 cm by given formula
R =
......................1
put here value
1 ×
=
solve we get
v = 91428571 m/s
and with radii 2.40 from equation 1
R =

2.4 ×
=
solve we get
v1 = 219428570 m/s
so
now we calculate energy of incident electron
KE = 0.5 m (v² + v1² )
KE = 0.5 ×9.1×
× (91428571² + 219428570² )
KE = 2.57 ×
J
KE = 2.57 ×
J × 6.242 ×
KE = 160.41 keV