Structure Of Atom Ques 20

20. The measurement of the electron position if associated with an uncertainty in momentum, which is equal to $1 \times 10^{-18}$ $ g $ $cm$ $ s^{-1}$. The uncertainty in electron velocity is,

(mass of an electron is $9 \times 10^{-28} $ $g$ )

[2008]

(a) $1 \times 10^{9}$ $cm $ $s^{-1}$

(b) $1 \times 10^{6} $ $cm $ $s^{-1}$

(c) $1 \times 10^{5} $ $cm $ $s^{-1}$

(d) $1 \times 10^{11}$ $ cm$ $ s^{-1}$

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Answer:

Correct Answer: 20.(a)

Solution:

  1. (a) $\Delta p=m \Delta v$

Substituting the given values of $\Delta x$ and $m$, we get $1 \times 10^{-18} $ $g$ $cm $ $s^{-1}=9 \times 10^{-28} g \times \Delta v$

or $\Delta v=\frac{1 \times 10^{-18}}{9 \times 10^{-28}}$

$=1.1 \times 10^{9} cm s^{-1} \simeq 1 \times 10^{9} $ $cm $ $s^{-1}$