We have a copper wire of resistance R . The wire is pulled so that its length is doubled (temperature remains constant). Find the new resistance of the wire in terms of its original resistance.
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Answer:
According to Ohm's law, current in the circuit is proportional to the voltage.
R = ρl/A,
where ρ is considered resistivity of the material.
Let
R1 = ρL/A and
R2 = ρ.2L/(A/2) =4.
ρL/A = 4R1.
Therefore, the new resistance of the conductor is four times the original resistance.
According to Ohm's law, current in the circuit is proportional to the voltage.
R = ρl/A,
where ρ is considered resistivity of the material.
Let
R1 = ρL/A and
R2 = ρ.2L/(A/2) =4.
ρL/A = 4R1.
Therefore, the new resistance of the conductor is four times the original resistance.
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Electrical Resistance of a conductor is the opposition or obstruction offered to the passage of electrons by the material of the conductor. Also, according to Ohm's law, the current in a circuit is proportional to the voltage: V= IR, R is the proportionality constant called resistance. 2. (i) We have R = ρl/A, where ρ is the resistivity of the material. Let R1 = ρL/A and R2 = ρ.2L/(A/2) =4. ρL/A = 4R1. So the new resistance is 4 times the original resistance. (ii) Resistivity is independent of the length and area of cross section of the wire and hence it will not change.
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