Question

A charged particle is fired at an angle to a uniform magnetic field directed along the X-axis during it's motion along helical path if the pitch of helix is equal to maximium distance of the particle from the X-axis, then

Answer 1

Explanation:

Pitch =(2π

ϕB

m

)vcosθ

Also mvsinθ=QBR

For motion perpendicular to the magnetic field

Or,r=

QB

mv

sinθ

Maximum distance of the particle from the x-axis = 2r

∴[2π

QB

m

]vcosθ=2

QB

mv

sinθ

or, tanθ=π

Hence (A) & (D) are correct.