Question

Uncertainity in the position of an electron (mass = 9.1 ´ 10–31 Kg) moving with a velocity 300 m.sec–1, Accurate upto 0.001%, will be : (h = 6.63 ´ 10–34 J-s)

• A. 19.2 ´ 10–2 m
• B. 5.76 ´ 10–2 m
• C. 1.92 ´ 10–2 m
• D. 3.84 ´ 10–2 m

Answer 1

Answer: (C)

1.92 ´ 10–2 m

Answer 2

According to Heisenberg's uncertainity principle

$\Delta x \times \Delta p = \frac{h}{4\pi}$

}{;\Delta v = \frac{0.001}{100} \times 300 = 3 \times 10^{- 3}ms^{- 1}}$$ $$\therefore\Delta x = \frac{6.63 \times 10^{- 34}}{4 \times 3.14 \times 9.1 \times 10^{- 31} \times 10^{- 3}} = 1.29 \times 10^{- 2}m.$$