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%
From NCERT
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 |
 82%
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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 A1 and the other one has a square cross-section of area A2. The ratio A1/A2 is:

1. \(1.5\) 2. \(1\)
3. \(0.8\) 4. \(2\)
Subtopic:  Derivation of Ohm's Law |
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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%
From NCERT
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 |
 79%
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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From NCERT
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 \(\sigma_1\) 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 |
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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)
Subtopic:  Derivation of Ohm's Law |
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