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i'm blur with this q.

a capacitor discharges through a resistor made of a length of wire. the time constant of the circuit is [tau1]. when the resistor is substituted with another wire made of the same metal but of twice the diameter and twice the length of the first wire, the time constant of the circuit is [tau2]

what is the ratio of [tau2] : [tau1]

the answer i get is 2 : 1

but the answer is 1 : 2

please explain the method i should use.

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# Homework Help: Capacitor -> time constant

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