A charged particle of mass m having kinetic energy K passes ...

CBSE Class 12 Physics 2026 All Sets Paper

Question : 8 of 16

Marks: +1, -0

A charged particle of mass m having kinetic energy K passes undeflected through a region with electric field

{E}↖{→}

and magnetic field

{B}↖{→}

acting perpendicular to each other. The mass m of the particle will be:

Solution:

From the condition of zero deflection:

v = \;{E}/{B}

Substitute this value of v into the kinetic energy expression:

K = \;{1}{2}/{m} (\;{E}/{B})^2

K = \;{mE^2}/{2B^2}

Rearranging to find the mass m:

m = \;{2KB^2}/{E^2}

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