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2. Electric Potential and Capacitance
medium
Two insulating plates are both uniformly charged in such a way that the potential difference between them is $V_2 - V_1 = 20\ V$. (i.e., plate $2$ is at a higher potential). The plates are separated by $d = 0.1\ m$ 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
$32 \times 10^{-19} $ $m/s$
B
$2.65 \times 10^6 $ $m/s$
C
$7.02 \times 10^{12}$ $ m/s$
D
$1.87 \times 10^6 $ $m/s$
(AIEEE-2006)
Solution
${e V=\frac{1}{2} m v^{2}}$
${\Rightarrow v=\sqrt{\frac{2 e V}{m}}=\sqrt{\frac{2 \times 1.6 \times 10^{-19} \times 20}{9.1 \times 10^{-31}}}}$
${=2.65 \times 10^{6} \,\mathrm{m} / \mathrm{s}}$
Standard 12
Physics
