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# Physics CIE 9702 Paper 21

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1. (Original post by olmomiau)
You got both right. I just realized that length of wire does not affect mean drift velocity as, if the current is to remain constant, the same number of electrons will have to pass a point per unit time, not travel the whole length of the wire.
Do you remember how many marks this first ratio was worth? Was it 2 or 3?
I think you are wrong here. Length does effect the current as increase in length increases Resistance and thus decreases current for constant voltage. so if current decreases by a factor of 2 so v also decreases by a factor of 2.
so the ans is either 8:1 or 2:1 not sure which :P
2. (Original post by Some one)
I think you are wrong here. Length does effect the current as increase in length increases Resistance and thus decreases current for constant voltage. so if current decreases by a factor of 2 so v also decreases by a factor of 2.
so the ans is either 8:1 or 2:1 not sure which :P
Yes, but it was a series circuit, so the current is the same anywhere in the circuit. It is the p.d. what can vary depending on the resistance.

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