1.

A student has a resistance wire of 1 ohm. If the length of this wire is 50 cm, to what length he should stretch it uniformly so as to obtain a wire of 4 ohm resistances? justify your answer.

Answer»

He should strech the wire upto 200cm for getting 4 ohm resistance as R =ρ*l/Atherefore 1 =ρ*50/A andρ/A = 1/50 ---------- (1) Now resistance = 4 ohm R =ρ*l/A4=ρ*l/Afrom (1)ρ/A = 1/50 so 4 = (1/50) land l = 200cm



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