Question

a student has a resistance wire of 1 ohm if the length of wire is 50 cm to what lengtg it should strech uniformly so as to obtain wire of 4 ohm resistance

Answer 1

Answer:

Explanation:

He should strech the wire upto 200cm for getting 4 ohm resistance

as R =ρ*l/A

 therefore

1 =ρ*50/A

and

ρ/A = 1/50 ---------- (1)

Now resistance = 4 ohm

R =ρ*l/A 

4 =ρ*l/A  

from (1)

ρ/A = 1/50 so

4 = (1/50)  l

 and l = 200 cm