The resistance of a wire is $$R$$ ohm. If it is melted and stretched to $$n$$ times its original length, its new resistance will be:
1. $$nR$$
2. $$\frac{R}{n}$$
3. $$n^2R$$
4. $$\frac{R}{n^2}$$

Subtopic:  Derivation of Ohm's Law |
82%
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NEET - 2017
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A wire made of a metal of uniform resistivity $$1.0\times 10^{-6}~\Omega{\text{-m}}$$  is $$2.0~\text{m}$$ long and has a diameter of $$2.0\times 10^{-3}~\text{m}$$. What is the electrical resistance of this length of the wire?
1. $$\dfrac {2.0 ~\times~10^{-3}}{\pi} ~\Omega$$
2. $$5.0 ~\times~10^{-13}\pi~\Omega$$
3. $$\dfrac {1.0}{2\pi}~\Omega$$
4. $$\dfrac{2.0}{\pi}~\Omega$$
Subtopic:  Derivation of Ohm's Law |
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Two solid conductors are made up of the same material and have the same length and the same resistance. One of them has a circular cross-section of area ${A}_{1}$ and the other one has a square cross-section of area ${A}_{2}$. The ratio ${A}_{1}/{A}_{2}$ is:

 1 $$1.5$$ 2 $$1$$ 3 $$0.8$$ 4 $$2$$
Subtopic:  Derivation of Ohm's Law |
82%
From NCERT
NEET - 2020
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A wire of resistance $$4~\Omega$$ is stretched to twice its original length. The resistance of a stretched wire would be:

 1 $$4~\Omega$$ 2 $$8~\Omega$$ 3 $$16~\Omega$$ 4 $$2~\Omega$$
Subtopic:  Derivation of Ohm's Law |
82%
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AIPMT - 2013
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The specific resistance of a conductor increases with:

 1 increase in temperature. 2 increase in cross-section area. 3 increase in cross-section and decrease in length. 4 decrease in cross-section area.

Subtopic:  Derivation of Ohm's Law |
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From NCERT
AIPMT - 2002
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The plot of current $$I~\text{(A)}$$ flowing through a metallic conductor versus the applied voltage $$V~\text{(volt)}$$ across the ends of a conductor is:

 1 2 3 4
Subtopic:  Derivation of Ohm's Law |
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NEET - 2022
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The current-voltage graph for a given metallic conductor at two different temperatures $$T_{1}$$ and $$T_{2}$$ is as shown in the figure. Then:

1. $$T_{1}=T_{2}$$
2. $$T_{2}>T_{1}$$
3. $$T_{1}>T_{2}$$
4. nothing can be said
Subtopic:  Derivation of Ohm's Law |
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The dependence of resistivity $$(\rho)$$ on the temperature $$(T)$$ of a semiconductor is, roughly, represented by:

 1 2 3 4
Subtopic:  Derivation of Ohm's Law |
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Two metal wires of identical dimensions are connected in series. If ${\mathrm{}}_{}$$$\sigma_1$$ $\mathrm{and}$ $$\sigma_2$$ are the conductivities of the metal wires respectively, the effective conductivity of the combination is:

 1 $$\frac{2\sigma_1 \sigma_2}{\sigma_1+\sigma_2}$$ 2 $$\frac{\sigma_1 +\sigma_2}{2\sigma_1\sigma_2}$$ 3 $$\frac{\sigma_1 +\sigma_2}{\sigma_1\sigma_2}$$ 4 $$\frac{\sigma_1 \sigma_2}{\sigma_1+\sigma_2}$$

Subtopic:  Derivation of Ohm's Law |
63%
From NCERT
NEET - 2015
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Consider a thin rectangular sheet of side $$L,$$ width $$b$$ and thickness $$t,$$ made of a material of resistivity $$\rho$$. The resistance between two opposite faces, shown by the shaded areas in the figure is:
 1 directly proportional to $$b$$ 2 inversely proportional to $$t$$ 3 inversely proportional to $$L$$ 4 both (1) and (2)