Why resistance will increase to 3 times when length is increased 3 times and will not increase to 9 times?

Asked by ms0851000 | 11th Mar, 2019, 05:38: PM

Expert Answer:

R = ρ l/ A ... (1) 
If l increases by 3 times then the changed resistance Ris given as,
Rc = ρ(3 l)/ A 
Thus, this can be written as,
Rc = 3(ρl/ A) ... (2) 
From (1) and (2),
Rc = 3 R
Hence, resistance increases by 3 times with an increase in its length by 3 times.
Also, from the formula, it is clear that resistance is directly proportional to the length of the wire. 

Answered by Shiwani Sawant | 11th Mar, 2019, 06:09: PM