Q12. A 4-Ohm resistance wire is doubled up by folding Calculate the new resistance of the
wire. (1)
Answers
Explanation:
when a wire is doubled up its length becomes half and cross section area becomes double.
R =p l/ A = 4 ohm........(1)
R new = p (l/2) /(2A)
= pl/(4A)
= (1/4) (pl/A) using eq 1
= 4/4 = 1 ohm
Answer:
Two ways to answer this.
1/ As an english grammar question. You say …resistance of 4 Ohm and is doubled…what is it’s resistance. Answer is 8 ohm as you did say you doubled it. It being the 4 ohm.
We know
R=ρ 1/A
, now area becomes half and length is double .
R1 =ρ 21/A/2 =ρ 41/A
=4R
2/ As a practical electrical question. You double over the wire and connect them in parallel, so resistance will halve by shortening and halve by doubling to 1 ohm.
Explanation:
when a wire is doubled up its length becomes half and cross section area becomes double.
R =p I/ A = 4 ohm..(1)
R new = p (1/2)/(2A)
= pl/(4A)
= (1/4) (pl/A) using eq 1
= 4/4 = 1 ohm