IIT JEE , AIEEE Forum - Physics , Magnetism

Prakriteesh

An electron is projected horizontally with a kinetic energy 10 kev. A magnetic field of strength 1.0 X 10^-7 T exists in the vertically upward direction. Calculate the sideways deflection of the electron in traveling through 1m. Make appropriate approximations.

Ans: 1.5 cm approx.

pink_ele

easy hai yaar!!!!!!!!!!

look

electron follows projectile motion towards the feiel force

ok

1/2mv²=1o kev

calculate v frm this

F=ma=bvqsin

calculate

a frm this

now

horizontal motion

s=vt

t=(1)/v

also vertically

s=1/2 at²

s=a/(2v²)

uwill get ans

if hav any prob nugdge me

Prakriteesh

Hi pink_ele, I couldn't understand why the motion should be projectile. We got that if a charge is projected in a magnetic field then its motion is either circular or helical, because the magnetic force is always perpendicular to the velocity of the particle (in projectile motion force is not always perpendicular to velocity). Here, the angle between the field and the velocity, i.e. theta = 90 degree, so the path should be circular. Moreover, even if we consider it to be projectile and solve the problem, still the answer comes to be 0.00015 m = 0.015 cm.

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