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Ch 22: Electric Charges and Forces
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Non è quello che usi tu?Cambia libro di testo
Capitolo 22, Problema 4b

A glass rod that has been charged to +12 nC touches a metal sphere. Afterward, the rod’s charge is +8.0 nC. How many charged particles were transferred?

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Understand the problem: The glass rod initially has a charge of +12 nC, and after touching the metal sphere, its charge decreases to +8.0 nC. This means some charge was transferred from the rod to the sphere. The goal is to calculate the number of charged particles (electrons) transferred.
Calculate the amount of charge transferred: Subtract the final charge of the rod from its initial charge. The formula is ΔQ = Q_initial - Q_final, where Q_initial = 12 nC and Q_final = 8.0 nC. This will give the charge transferred in coulombs.
Convert the charge transferred from nanocoulombs (nC) to coulombs (C): Use the conversion factor 1 nC = 1 × 10⁻⁹ C. Multiply the charge transferred (ΔQ) by this factor to express it in coulombs.
Determine the number of electrons transferred: Use the relationship between charge and the elementary charge of an electron. The formula is N = ΔQ / e, where e = 1.6 × 10⁻¹⁹ C (the charge of a single electron). Divide the charge transferred (in coulombs) by the elementary charge to find the number of electrons.
Interpret the result: The value of N represents the number of electrons transferred from the rod to the sphere. Since electrons are negatively charged, the transfer of electrons reduces the positive charge on the rod.

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