The current in an electron beam in a cathode-ray tube is measured to be 280 µA.How many electrons hit the screen in 50 s? (e = 1.6 × 10−¹⁹ C) A) 2.2 × 10¹¹ electrons B) 8.8 × 10¹⁶ electrons C) 8.8 × 10¹⁵ electrons D) 2.2 × 10¹⁵ electrons

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Quizplus · Accepted Answer

The number of electrons is calculated by dividing the total charge by the charge of one electron. Total charge = current × time = 280 µA × 50 s = 14,000 µC = 14 × 10^-3 C. Number of electrons = (14 × 10^-3 C) / (1.6 × 10^-19 C/electron) = 8.8 × 10^16 electrons.

The Current in an Electron Beam in a Cathode-Ray Tube