A piece of wire of resistance 20 ohm is drawn out
show that its length is increase to twice its original
length. Calculate the resistance of the wire in the
new situation?
Answers
Answered by
14
Explanation:
As we know, When the length is doubled, area of the wire becomes half. R = 80 ohm
Answered by
40
Answer
The new resistance is 80 ohm.
Explanation :-
Given,the length is doubled. Let the initial length be l and final be l' .The corresponding areas to be A and A'.
Volume remains constant.Hence, V = V' .
=> l × A = l' × A'
Given, l' = 2l
=> l × A = 2l × A'
=> A' = A/2 .
=>A' = 0.5A
Now, Original resistance = 20 ohm.
=> pl/A = 20 (Assuming p = resistivity)
R' = p×2l/0.5A
=> R' = 4 × pl/A = 4 × 20
=> R' = 80 ohm
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