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The charge equivalent to 6×10¹⁸ electrons is _______.

Asked in GSEB Board March 2020 · Properties of charge

• (1) -1 C
• (2) 1 C
• (3) 1 mC
• (4) -1 mC

Step-by-step solution

Why the other options are wrong

• (2) This drops the sign. Electrons are negative, so 6×10¹⁸ of them carry -0.96 C, about -1 C.
• (3) Wrong sign, and 1000 times too small. No single slip gives 1 mC: ne = (6×10¹⁸)(1.6×10⁻¹⁹) = 0.96 C, close to a coulomb, not a millicoulomb.
• (4) Right sign but 1000 times too small. No single slip gives -1 mC: 6×10¹⁸×1.6×10⁻¹⁹ = 0.96, so the charge is about -1 C.

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