An electron at point A in (Figure 1) has a speed v0 of 1.40×106
m/s . a. Find the magnitude of the magnetic field that will cause
the electron to follow the semicircular path from A to B. b. Find
the time required for the electron to move from A to B. c. What
magnetic field would be needed if the particle were a proton
instead of an electron?
Answer
radius of circular path is r = mv/qB
so D = 10 cm
r = 5 cm
magnetic field B = mv/qr
here semicircle
for electron :
B = (9.11*10^-31 * 1.4*10^6)/(1.6*10^-19 * 5*10^-2)
B = 1.6 *10^-4 Tesla
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Circumference C = 2pi R
C = 2*3.14* 0.05 = 0.314 m
length of semi circle = 2 piR /2 = 0.157 m
so
time = s/v
t = 0.157/1.4 e 6
t = 112.1 ns
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for proton,
B = (1.67*10^-27 * 1.4*10^6)/(1.6*10^-19 * 5*10^-2)
B = 0.29 Tesla
