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Grade 12th PassMagnetism

A particle of charge q and mass m starts from the origin under an electric field E along x axis and magnetic field B along x axis with velocity v.
After what time the velocity of the particle will be 2v?

Profile image of ANIMESH BHAR
7 Years agoGrade 12th Pass
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1 Answer

Profile image of mahima pareek
7 Years ago
 
The magnetic field here is parallel to the velocity and hence no effect on it .
By.       F(B) = q [ v ⅹ B]
  So Electric force will affect its velocity
    F(E) = qE 
So acceleration = qE/m
By first equation of motion
i. e .   v = u +a*t 
       2v =  v  + qE/m*t
t =  mv/qE is the answer 
Approve if correct