a wire of resistance R ohm is dauble on it.calculate new resistance.
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We consider wire is doubled on it means to fold the length of wire. It means its length will get half and area of cross section will get doubled.
∴ Let the resistance of the wire originally 'R'' of length 'L' and area of cross-section 'A' with resistivity of material is 'p',
Then
R'= p l/A = R ohm
Now, for new arrangement,
p" = p
l"= l / 2
A"= 2A
Thus,
R"= p"l"/A"= p"(l"/2) ÷ 2A = 1/4 (p l / A) = 1/4.R1 = 1/4Ω.
amitkumar5795:
i thik your answer is incorrect because ,if the resistance is get dauble than its length be get dauble (RESISTANCE is directly proportional to LENGTH) and its area of cross-section is get half not dauble(RESISTANCE is inversely proportional to AREA OF CROSS-SECTION) so above conclusion your answer is incorrect.
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