Dual Nature of Radiation and Matter - Result Question 60

64. An electron of mass $m$ and charge $e$ is accelerated from rest through a potential difference of $V$ volt in vacuum. Its final speed will be

[1996]

(a) $\frac{eV}{2 m}$

(b) $\frac{eV}{m}$

(c) $\sqrt{\frac{2 eV}{m}}$

(d) $\sqrt{\frac{eV}{2 m}}$

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Answer:

Correct Answer: 64. (c)

Solution:

  1. (c) Kinetic energy of electron accelerated through a potential $V=eV$

$\Rightarrow \frac{1}{2} m v^{2}=eV$

$\Rightarrow v^{2}=\frac{2 eV}{m} \Rightarrow v=\sqrt{\frac{2 eV}{m}}$