An electron at point A in the figure (Figure 1) has a speed v0

of 1.10×106 m/s . a) Find the magnitude of the magnetic field that will cause the

electron to follow the semicircular path from A to

B. A B b)Find the time required for the electron to move from

A to B.

A B

givne

chargeis electron q = – 1.6*10^-19 C,

speed V0 = 1.10*10^6 m/s

moving along the semi circle of lenght pi*r , r is radius of the

circle 5.0*10^-2 m

here the force acting on the electron is F =

B*q*V fp= mV^2/r (centripetal

force)

a) B = mV^2/(r*q*V) =

m*V/r*q

= (9.1*10^-31

*1.10*10^6 )/ (0.05*(-1.6*10^-19))

= 0.000125125 T =

125.125 micro tesla = 1.25125*10^-4 T

B = 1.25*10^-4 T

b) Time taken T = pi*r / V = 3.14*0.05/(1.10*10^6) =

1.42727*10^-7 seconds

T = 1.43*10^-7 s