The figure shows a graph for electric potential versus position along the x -axi

Question

The figure shows a graph for electric potential versus position along the x-axis. An electron is originally at point A, moving in the positive x-direction. How much kinetic energy does it need to have at point A in order to be able to reach point E (with no forces acting on the electron other than those due to the indicated potential)? Points B, C, and D have to be passed on the way.
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The figure shows a graph for electric potential versus position along the x-axis. An electron is originally at point A, moving in the positive x-direction. How much kinetic energy does it need to have at point A in order to be able to reach point E (with no forces acting on the electron other than those due to the indicated potential)? Points B, C, and D have to be passed on the way.

Explanation / Answer

Answer : 7.2*10-18 Jolues

Explanation :

Point A is at a higher potential than B. Since the natural tendency of an electron is to move from region of lower potential to higher potential. Since here the electron has to move opposite, that is, from higher to lower potential, energy has to be spent.

We know, energy E = q*V , where 'q' is the charge, and 'V' is the potential difference = Vf-Vi

Given :

In this case, q = -1.6*10-19 C ( charge of an electron )

V = Vf-Vi = 55-100 = -45 V

So, energy required, E = q*V = (-1.6*10-19)*(-45) = 7.2*10-18 Jolues

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