Question

Determine the magnetic field required to bend a beam consisting of electrons of speed 3x10⁷ m/s in a circle of radius 5 cm.

Answer 1

For the case of transverse field:
BeV = mv² / R
R = (m / e) (v / B)
For an electron with velocity 5 cm

5 × 10-2 = (9.1 × 10-31 / 1.6 ×10-19)×(3 × 107 / B)
B= (9.1× 10-31 / 1.6 ×10-19) × (3 ×107 / 5 ×10-2)
B = 3.413×10-3 wb/m2