Heisenberg Uncertainty Principle Velocity of Electron | JEE Main PYQ | Structure of Atom
Q. Based on Heisenberg's uncertainty principle, the uncertainty in the velocity of the electron to be found within an atomic nucleus of diameter 10−15 m is _____ × 109 m s−1 (nearest integer).

Given : mass of electron = 9.1 × 10−31 kg
Planck's constant (h) = 6.626 × 10−34 J s
Value of π = 3.14

Explanation
Step 1: Heisenberg Uncertainty Principle

Δx · Δp ≥ h / 4π

Step 2: Convert momentum uncertainty to velocity

Δp = m · Δv
Δv ≥ h / (4π m Δx)

Step 3: Substitute values

Δx = 10−15 m
m = 9.1 × 10−31 kg

Δv ≥ 6.626 × 10−34 / (4 × 3.14 × 9.1 × 10−31 × 10−15)

Δv ≈ 5.8 × 1010 m s−1

Correct Answer = 58

Updated for JEE Main 2026: This PYQ is important for JEE Mains, JEE Advanced and other competitive exams. Practice more questions from this chapter.

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