A student makes a homemade resistor from a graphite pencil $5.00 \mathrm{cm}$ long, where the graphite is $0.05 \mathrm{mm}$ in diameter. The resistivity of the graphite is $\rho=1.38 \times 10^{-5} \Omega / \mathrm{m} .$ The homemade resistor is place in series with a switch, a 10.00 -mF capacitor and a 0.50 -V power source. (a) What is the $R C$ time constant of the circuit? (b) What is the potential drop across the pencil 1.00 s after the switch is closed?
Added by Bradley U.
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38 \times 10^{-5} \, \Omega/m \), \( L = 5.00 \, cm = 0.05 \, m \), and \( r = 0.025 \, mm = 0.025 \times 10^{-3} \, m \). Show moreā¦
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