Measurement of an electron's position introduces an uncertainty in momentum equal to 1 times 10^ -18 g cm s^ -1 . The uncertainty in electron velocity (mass of electron = 9 times 10^ -28 g) is:

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NEET Chemistry QUESTION #7351

Question 1

Measurement of an electron's position introduces an uncertainty in momentum equal to \(1 \times 10^{-18}\) g cm s\(^{-1}\). The uncertainty in electron velocity (mass of electron \(= 9 \times 10^{-28}\) g) is:

\(1 \times 10^{11}\) cm s\(^{-1}\)
\(1 \times 10^{9}\) cm s\(^{-1}\)✔️
\(1 \times 10^{6}\) cm s\(^{-1}\)
\(1 \times 10^{5}\) cm s\(^{-1}\)

Correct Answer Explanation

Formula: \(\Delta v = \dfrac{\Delta p}{m}\)

\(\Delta v = \dfrac{1 \times 10^{-18}}{9 \times 10^{-28}} = \dfrac{1}{9} \times 10^{10} \approx 1 \times 10^9\) cm s\(^{-1}\)

This enormously large uncertainty in velocity illustrates why classical mechanics fails for electrons — they cannot have precisely defined trajectories.

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