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A cell connected to two resistors P and Q that are connected in parallel. The resistors are metal wires made of the same material. The length of P is L and the length of Q is 2L. The diameter of P is d/2 and the diameter of Q is d. The current through P is I1 and the current through Q is I2. What is the ratio I1/ I2?

I tried to express the resistance through the resistivity formula and then divide one by the another to get the current ratio. But an answer supposed to be D (ratio equal 8), and not 1/2. Would appreciate any tipenter image description here enter image description here

Mykyta Honcharenko
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  • What you have dis wod divided R2/R1. And that's why you got 1/2. Amdnm to get answer D. You need to have P length equal 2L and Q length L. – G36 Nov 01 '23 at 13:23

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I think the question is just wrong, and none of the choices is correct. I get the same 1/2 you do. P has 4x the resistance per length, and half the length, so P has 2x the resistance, and 1/2 the current.

If they had said "the diameter of P is d and the diameter of Q is d/2" then 8 would be a correct answer.

hobbs
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