Sat February 04, 2012 By: Lahari Nibhanupudi

The electrons in a particular beam each have a kinetic energy of 1.6*10 raised to -17 times j. What will be the magnitude and direction of the electric field that stops these electrons at a distance of 10cm?

Expert Reply
Mon February 06, 2012
The K.E. of the electrons will convert in to P.E. .
So the change in K.E.= change in P.E.
(Kf-Ki)= Uf-Ui
Kf-Ki= q( Vf-Vi)
Kf-Ki=q(E* d)
Kf=0, Ki=1/2 me v2
d=10 cm, q= charge on electron.
put the values and get the answer. 
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