Question

A 100 ohm nichrome wire is doubled on itself. The new resistance of this wire is
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Answer 1

Explanation:

Let, the resistance of the resistor is R, length of resistor is L and cross-sectional area is A.

We know, R∝L and R∝ $\frac{1}{a}$

Also, when the length of resistor is doubled its cross-section area is halved therefore due to combined effect of these two R will decrease.

Hence, the new resistance say $_(R){n}$ is

$_(R){n}$ =(4)R

$_(R){n}$ =(4)×100

$_(R){n}$ =400Ω

Answer 2

Answer:

25 ohms

Explanation:

doubled on it

100 ohm = resistivity × length

–-----------‐—------------------

a

= resistivity × length/2

–-----------‐—------------------

2a

100ohm/4 = 25 ohm is final answer