Electrons in a particle beam each have a kinetic energy of 4.5 × 10−¹⁷ J.What is the magnitude of the electric field that will stop these electrons in a distance of 0.6 m? (e = 1.6 × 10−¹⁹ C)

Question

Quizplus · Accepted Answer

The work done by the electric field to stop an electron with charge e and kinetic energy K is equal to the kinetic energy lost by the electron: 
W = -K = - 4.5 × 10^-19 J.
The work done by an electric field on an electron moving through a distance d is given by: 
W = eEd
where E is the magnitude of the electric field. Equating these two expressions for W and solving for E, we get: 
E = -K/(ed) = (4.5 × 10^-19)/(1.6 × 10^-19 × 0.6) = 4,687.5 N/C, which rounds to 4,688 N/C. 
Therefore, the correct answer is (C).

Electrons in a Particle Beam Each Have a Kinetic Energy