Physics question below?

Question

In a television set, electrons are accelerated from rest through a potential difference of 24 kV. The electrons then pass through a 0.28 T magnetic field that deflects them to the appropriate spot on the screen. Find the magnitude of the maximum magnetic force that an electron can experience.

Answer 1

(Potential energy P equal Voltage (V) time charge (q) of the electron)
P=Vq

(Kinetic energy (Ke) is half the product of mass (m) of an electron times the velocity (v) of the electron squared)
Ke=.5mv^2

Potentila energy gets converted in to kinetic energy
P=Ke
Then velocity is
v=sqrt(2Vq/m)

The force (F) on the electron of charge (q) moving with velocity (v) due to the magnetic field (B) is
F=qvB

Since v=sqrt(2Vq/m) then
F=q sqrt(2Vq/m) B
F=B sqrt((2 V q^3)/m)

m=9.1 E–31 kg
q=1.6 E–19 C
F=0.28 sqrt( (2 x 24 E3(1.6 E–19 )^3 / 9.1 E–31)
F=1.47E-11 N

Answer 2

Max Magnetic Force = qvB. Look up q. They give you B.

To find B, use conservation of energy.

Initial potential energy
=(Voltage)(charge)
=Final kinetic energy
=(1/2)(mass)(velocity)^2

Solve the above for velocity, which you plug into the first equation to get your answer.