Avelocity selector is built with a magnetic field of magnitude 5.2 t and an electric field of strength 4.6 × 10 ^4 n/c. the directions of the two fields are perpendicular to each other. at what speed will electrons pass through the selector without deflection? let the charge of an electron q = −1.6 × 10 ^ −19

a.8.8 × 10^3 m/s
b 2.4 × 10 ^ - 15 m/s
c 7.9 × 10 ^ 13 m/s
d 2.0 x 10 ^ 4 m/s

Option A that is 8.8 × 10^3 m/s

The magnetic field B is defined from the Lorentz Force Law, and specifically from the magnetic force on a moving charge. It says

Field-strength = BVqsinΔ

Since field are perpendicular so sin90 = 1

             v = 4.6/10^4 / 5.2

             v = 8846.15 m /s

The speed at which electrons pass through the selector without deflection = 8846.15 m /s

layer a is the exosphere and layer b is the thermosphere.   is the answer i think but i hope this .