An electron of mass ' m ' and charge ' q ' is accelerated from rest in a uniform electric field of intensity ' E '. The velocity acquired by it as it travels a distance ' l ' is ' v '. The ratio q m in terms of E , l and v is

Step-by-step solution

We know aligned & F=m a and F=q E & q E=m a & qE ~m = a ...(i) aligned According to equation of motion, v^2-u^2=2 a L aligned & v^2-0^2=2 a L & v^2=2 a L & a= v^2 2 L ...(ii) aligned From (i) and (ii), aligned & v ^2 2 ~L = qE ~m & q ~m = v ^2 2 EL = v ^2 2 E ( ~L = ) aligned