resistance of a wire of length 18 cm is 4 ohm if the wire is tripled on itself find the new resistance
Answers
Answered by
0
Let's say a wire having length L cross sectional area A have resistance R. If it is so stretched that its length becomes 3L so new length L' = 3L and when length is tripled by stretching the cross sectional area decreases to one-third.
The resistance of the wire is expressed as R=
A
ρL
where,
rho is the resistivity of the wire,
L is the length of the wire,
A is the area of coss section of the wire.
The new resistance is calculated as follows.
R=
3
A
ρ3L
=
A
9ρL
.
That is, the new resistance is nine times the old resistance.
Hence, the new resistance is 9×9=81ohms.
Similar questions