Charge is quantized in units of the elementary charge e = 1.602 × 10⁻¹⁹ C. Hence n = Q/e = 2/(1.602×10⁻¹⁹) ≈ 1.248×10¹⁹ electrons = 12.48×10¹⁸ electrons.
Formula / Key Relation
e = 1.602 × 10⁻¹⁹ C
n = Q/e
n = 2/(1.602×10⁻¹⁹)
≈ 1.248×10¹⁹ electrons
= 12.48×10¹⁸ electrons
Detailed Explanation
Concept & ReasoningEach electron carries charge magnitude e = 1.602 × 10⁻¹⁹ C. The number of electrons corresponding to a charge magnitude Q is obtained by dividing Q by e. The sign of electron charge is negative, but when a question asks 'how many electrons', the count is a positive number. Substituting Q = 2 C gives approximately 1.248 × 10¹⁹ electrons, which matches 12.48 × 10¹⁸.How to Solve It in the Exam1 C corresponds to about 6.24×10¹⁸ electrons; multiply by 2.Important Exam PointKeep scientific notation consistent before matching the option.Related Revision PathThis question sits in the revision path Basic…
Concept & Reasoning
Each electron carries charge magnitude e = 1.602 × 10⁻¹⁹ C. The number of electrons corresponding to a charge magnitude Q is obtained by dividing Q by e. The sign of electron charge is negative, but when a question asks 'how many electrons', the count is a positive number. Substituting Q = 2 C gives approximately 1.248 × 10¹⁹ electrons, which matches 12.48 × 10¹⁸.
How to Solve It in the Exam
1 C corresponds to about 6.24×10¹⁸ electrons; multiply by 2.
Important Exam Point
Keep scientific notation consistent before matching the option.
Related Revision Path
This question sits in the revision path Basic Electrical Engineering → Electric Charge → Charge Quantization .
Quick Trick
1 C corresponds to about 6.24×10¹⁸ electrons; multiply by 2.
Common Mistake
Do not multiply Q by e; electron count is charge divided by elementary charge.
Exam Tip
Keep scientific notation consistent before matching the option.
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