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Electric Charges and Fields — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsElectric Charges and Fields3 Marks
Question
Assume that each atom in a copper wire contributes one free electron. Estimate the number of free electrons in a copper wire having a mass of 6.4g (take the atomic weight of copper to be 64g mol-1.
✓

Answer

64 grams of copper have 1 mole
6.4 grams of copper have 0.1 mole
1 mole = No atoms
0.1 mole = (no × 0.1) atoms
= 6 × 1023 × 0.1 atoms = 6 × 1022 atoms
1 atom contributes 1 electron
6 × 1022 atoms contributes 6 × 1022 electrons.

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