Question

What is the velocity of a beam of electrons that goes undeflected when moving perpendicular to an electric and magnetic fields. E⃗ E→ and B⃗ B→ are also perpendicular to each other and have magnitudes 8500 V/mV/m and 6.3×10−3 TT , respectively.

Answer 1

The given question is incomplete. The complete question is as follows.

What is the velocity of a beam of electrons that goes undeflected when moving perpendicular to an electric and magnetic fields. E⃗ E→ and B⃗ B→ are also perpendicular to each other and have magnitudes 8500 V/mV/m and 6.3×10−3 TT , respectively.

What is the radius of the electron orbit if the electric field is turned off?

Explanation:

It is known that,

           v = $\frac{E}{B}$

              = $\frac{8500 V/m}{6.3 \times 10^{-3}}$

              = 1349206 m/s

Also,     r = $\frac{mv}{qB}$

               = $\frac{9.1 \times 10^{-31} \times 1349206 m/s}{1.6 \times 10^{-19} \times 6.3 \times 10^{-3}}$

               = $1218033.194 \times 10^{-9}$

or,            = $12.18 \times 10^{-5}$ m

Thus, we can conclude that velocity of a beam of electrons that goes undeflected is $12.18 \times 10^{-5}$ m.