In a crossed field, the magnetic field induction is 2.OT and electric field intensity is `20xx10^(3)v/m`. At which velocity the electron will travel In a straight line without the effect of electric and magnetic fields ?

Options

A. `(20)/(1.6)xx10^(3)ms^(-1)`
B. `10xx10^(3)ms^(-1)`
C. `20xx10^(3)ms^(-1)`
D. `40xx10^(3)ms^(-1)`

Answer

B

Explanation

In case of motion of electron to be unaffected by electric and magnetic field(i.e. E and B) the resultant of both the fields should be zero. Hence, evB=eE
where, e=electronic charge and v=velocity of electron
`Rightarrowv=(E)/(B)v=(20xx10^3)/(2.0)=10xx10^(3)ms^(-1)`