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Grade 10Electromagnetic Induction

A copper wire of radius 0.1 mm and resistance 1 kΩ is connected across a power supply of 20 V. (a) How many electrons are transferred per second between the supply and the wire at one end? (b) Write down the current density in the wire.

Profile image of Hrishant Goswami
12 Years agoGrade 10
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1 Answer

Profile image of Jitender Pal
12 Years ago
Sol. r = 0.1 mm = 10^-4 R = 1 KΩ = 10^3 Ω, V = 20 V a) No.of electrons transferred i = V/R = 20/10^3 = 20 * 10^-3 = 2 * 10^-2 A q = i t = 2 * 10^-2 * 1 = 2 * 10^-2 C. No. of electron transferred = 2 * 10^-2/1.6 * 10^-19 = 2 * 10^-17/1.6 = 1.25 * 10^17. b)Current density of wire = i/A = 2 * 10^-2/π * 10^10^-8 = 2/3.14 * 10^+6 0.6369 * 10^+6 = 6.37 * 10^5 A/m^2.