Q. If an electron moves from rest from a point at which potential is $50$ V to another point at which potential is $70$ V, then its kinetic energy in the final state will be
A) $3.2 \times 10^{- 20}$J
B) $3.2 \times 10^{- 18}$J
C) $3.2 \times 10^{- 19}$J
D) Zero
Explanation
(b) The kinetic energy acquired by the particle is
$KE = q\mathrm{\Delta}V$
Where q is charged and $\mathrm{\Delta}V$ the change is potential difference.
Given, q $= e =$1.6$\times 10^{- 19}$ C
$\mathrm{\Delta}V =$ $V_{2} - V_{1} = 70 - 50 = 20\ $V
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ KE = 1.6 \times 10^{- 19} \times 20 = 3.2 \times 10^{- 18}$J
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.