物理 磁力 電子的速率

用能量守恆角度

1/2 mv2 = eV

1/2 (9.11 X 10-31)v2 = (1.6 X 10-19)(250)

電子速度，v = 9.37 X 106 ms-1


用eBv = mv2 / r

r = mv / eB

r = (9.11 X 10-31)(9.37 X 106) / (1.6 X 10-19)(10 X 10-3)

軌道半徑，r = 5.34 X 10-3 m


用v = rw

角速度，w = v/r = (9.37 X 106)/(5.34 X 10-3) = 1.76 X 109 rads-1

再根據 T = 2pi / w

週期，T = 2pi / (1.76 X 109) = 3.58 X 10-9 s