If a 9 ohm wire is tripled around itself. What will be change in resistance
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Answer:
R' = 1 Ohm
Explanation:
Given resistance (R) = 9 Ohm
Initial Length = L
Initial Area of cross section = A
Let resistivity = x
Then, from R = xL/A, 9 = xL/A - (eqn.1)
Now,
New length = l = L/3
New Area of cross section = a = 3A
Resistivity remains the same, ie x.
Let new resistance be R'.
From R = xL/A, R' = x(L/3)(1/3A)
or, R' = xL/9A
or, 9R' = xL/A - (eqn.2)
From eqn.1 and eqn.2, we get
9 = 9R'
or, R' = 9/9 = 1 Ohm
Thus, new resistance = R' = 1 Ohm.
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