Q.
Two insulating plates are both uniformly charged in such a way that the potential difference between them is $V_{2} - V_{1} = 20V.$ ($i.e.$ plate 2 is at a higher potential). The plates are separated by $d = 0.1m$ and can be treated as infinitely large. An electron is released from rest on the inner surface of plate 1. What is its speed when it hits plate 2
$(e = 1.6 \times 10^{- 19}C,\ m_{e} = 9.11 \times 10^{- 31}kg)$
A) $7.02 \times 10^{12}\ m/s$
B) $1.87 \times 10^{6}\ m/s$
C) $32 \times 10^{- 19}\ m/s$
D) $2.65 \times 10^{6}\ m/s$
Explanation
(d) $v = \sqrt{\frac{2QV}{m}}$
$= \sqrt{\frac{2 \times 1.6 \times 10^{- 19} \times 20}{9.11 \times 10^{- 31}}} = 2.65 \times 10^{6}\ m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.