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An electron (q = −e, mass m) accelerated from rest through a potential difference V gains kinetic energy:
A½ e V
Be V
C2 e V
De V²
Answer & Solution
Correct answer: B. e V
1. Energy gained = work done by field = |q| V = e V.
2. Defines the electronvolt: 1 eV = energy gained by 1 e through 1 V = 1.6 × 10⁻¹⁹ J.
3. Speed: ½ m v² = e V ⇒ v = √(2 e V / m).
_Source: NCERT Class 12 Physics Ch 2 §2.10 (work-energy with field)_
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