A beam of electrons moving at a speed of 8 $\times$ 10⁴ m/s is undeflected when it passes through an electric field of 5 N/C perpendicular to its path and a magnetic field that is perpendicular to its path and also to that of the electric field.Calculate the strength of the magnetic field. A)1.60 $\times$ 10⁴ T B)6.25 $\times$ 10^-5 T C)7.81 $\times$ 10^-10 T D)3.13 $\times$ 10^-5 T E)1.25 $\times$ 10^-4 T

Question

Quizplus · Accepted Answer

For an electron beam to be undeflected by perpendicular electric and magnetic fields, the force due to the electric field (F_e = qE) must equal the force due to the magnetic field (F_m = qvB). Setting these equal gives E = vB, solving for B gives B = E/v. Substituting E = 5 N/C and v = 8×10^6 m/s gives B = 5/(8×10^6) = 6.25×10^-7 T.

A Beam of Electrons Moving at a Speed of 8 ×\times×

A Beam of Electrons Moving at a Speed of 8 $\times$