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Dielectric materials used in the manufacture of capacitors are characterized by conductivities that are small but not zero. Therefore, a cha
Question
Dielectric materials used in the manufacture of capacitors are characterized by conductivities that are small but not zero. Therefore, a charged capacitor slowly loses its charge by “leaking” across the dielectric. If a certain 3.25 µF capacitor leaks charge such that the potential difference decreases to half its initial value in 4 s, what is the equivalent resistance of the dielectric?
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Physics
4 years
2021-08-05T16:51:56+00:00
2021-08-05T16:51:56+00:00 1 Answers
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Answer:
Equivalent resistance of the dielectric= R =1.78 × 10^6 Ω
Explanation:
This is just an RC circuit, where
q = CVoe-t/RC.
V is proportional to q; so if V has lost half its value, so has q.
So we need R such that
e-t/RC = 0.5
Taking log on both sides, we get
-t/RC = ln(0.5)
R = -t/ln(0.5)C
= (-4 s)/[(3.25×10^-6 F)(-0.693147)]
= 1.78 × 10^6 Ω