CBSE 2026 · Region 5 · Set 1 · Q21 · 2 marks

Suppose a pure Si crystal has $\displaystyle 5 \times 10^{28}$ atoms per $\displaystyle \mathrm{m}^{3}$. It is doped with $\displaystyle 5 \times 10^{22}$ atoms per $\displaystyle \mathrm{m}^{3}$ of Arsenic. Calculate the majority and minority carrier concentration in the doped silicon. (Given : $\displaystyle \mathrm{n}_{\mathrm{i}}=1 \cdot 5 \times 10^{16} \mathrm{~m}^{-3}$ )

CBSE Class 12 Physics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.