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Solve the following.
An alpha particle is made to move through two plates apart. The speed with which it enters the gap…
An alpha particle is made to move through two plates $10\text{ cm}$ apart. The speed with which it enters the gap in the first plate is $2.5\times10^6\text{ m s}^{-1}$. The particle exits the second plate with a velocity of $5\times10^6\text{ m s}^{-1}$.
Calculate the potential difference between the plates.
Answer
Answer
Official answer keyBy conservation of energy,
Change in K.E. + Change in P.E. = 0
or $\Delta K + q\Delta V = 0$
$\Delta V = -\frac{\Delta K}{q} = -\frac{\frac{1}{2}m(v^2 - u^2)}{q} = -\frac{\frac{1}{2} \times 6.64 \times 10^{-27} \times (25 - 6.25) \times 10^{12}}{3.2 \times 10^{-19}} = -1.95 \times 10^5$ V
Final answer: $-1.95 \times 10^5$ V
From ISC 2025 Practice Physics, question 79(a).
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