Grade 12th passElectric Current
A wire of resistance 10 ohm is stretched 20% determinant its new resistance
A wire of resistance 10 ohm is stretched 20% determinant its new resistance
2 Answers
Arun
resistance is given by, R = ρl/A
R = ρl²/(Al) = ρl²/V.....(1), where V is volume of wire.
at constant volume, V resistance of wire depends on only length of wire.
as it is clear in expression (1), resistance is directly proportional to square of its length.
now, according to question,
length is increased by 20%
so, new length of wire = l + 20% of l
= l + 0.2l = 1.2l
now, new resistance , R' = ρ(1.2l)²/V....(2)
from equations (1) and (2),
R'/R = 1.44 => R' = 1.44R
it is given initial resistance, R = 10ohm
so, R' = 1.44R = 14.4ohm
Vikas TU
Dear student
resistance is given by, R = ρl/A
R = ρl²/(Al) = ρl²/V.....(1), where V is volume of wire.
at constant volume, V resistance of wire depends on only length of wire.
as it is clear in expression (1), resistance is directly proportional to square of its length.
now, according to question,
length is increased by 20%
so, new length of wire = l + 20% of l
= l + 0.2l = 1.2l
now, new resistance , R' = ρ(1.2l)²/V....(2)
from equations (1) and (2),
R'/R = 1.44 => R' = 1.44R
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