A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity then

Options

A. turn to its right
B. turn to its left
C. keep moving in the same but its speed will increase
D. keep moving in the same but its speed will decrease

Answer

D

Explanation

`rarr vec(E) = E_(0) hat(i)`
`rarrvec(B) = B_(0) hat(i)`
`rarrvec(v) = v_(0)hat(i)`
`vec(F)_(m) = 0, vec(F)_(e) = -eE_(0) hat(i)`

Retardation `= (eE)/(m)`