A particles of mass `1kg` and carrying positive charge `0.01C` is sliding down an inclined plane of angle `30^(@)` with the horizontal .An electric field `E` is applied to stop the particles.If the coefficient of friction between the particles and the surface of the plane is `(1)/(2sqrt(3))`. E must be

Options

A. 1260 V/m
B. 245 V/m
C. `140sqrt(3)`V/m
D. `490/(sqrt(3))` V/m

Answer

C

Explanation

`mg(sin alpha-mu cos alpha)- mu q E sin alpha- q E cos alpha`