The current in a wire varies with time according to the equation $$I=(4+2t),$$ where $$I$$ is in ampere and $$t$$ is in seconds. The quantity of charge which has passed through a cross-section of the wire during the time $$t=2$$ s to $$t=6$$ s will be:

 1 $$60$$ C 2 $$24$$ C 3 $$48$$ C 4 $$30$$ C

Subtopic:  Current & Current Density |
83%
From NCERT
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A charged particle having drift velocity of $$7.5\times10^{-4}~\text{ms}^{-1}$$ in an electric field of $$3\times10^{-10}~\text{Vm}^{-1}$$, has mobility of:
1. $$2.5\times 10^{6}~\text{m}^2\text{V}^{-1}\text{s}^{-1}$$
2. $$2.5\times 10^{-6}~\text{m}^2\text{V}^{-1}\text{s}^{-1}$$
3. $$2.25\times 10^{-15}~\text{m}^2\text{V}^{-1}\text{s}^{-1}$$
4. $$2.25\times 10^{15}~\text{m}^2\text{V}^{-1}\text{s}^{-1}$$

Subtopic:  Current & Current Density |
82%
From NCERT
NEET - 2020
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Drift velocity $$v_d$$ varies with the intensity of electric field as per the relation:
1. $$v_{d} \propto E$$
2. $$v_{d} \propto \frac{1}{E}$$
3. $$v_{d}= \text{constant}$$
4. $$v_{d} \propto E^2$$

Subtopic:  Current & Current Density |
78%
From NCERT
PMT - 1981
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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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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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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 |
64%
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The equivalent resistance between $$A$$ and $$B$$ for the mesh shown in the figure is:

 1 $$7.2$$  $$\Omega$$ 2 $$16$$  $$\Omega$$ 3 $$30$$  $$\Omega$$ 4 $$4.8$$  $$\Omega$$
Subtopic:  Combination of Resistors |
87%
From NCERT
NEET - 2020
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A potential divider is used to give outputs of $$2~\text{V}$$ and $$3~\text{V}$$ from a $$5~\text{V}$$ source, as shown in the figure.

Which combination of resistances, from the ones given below, $$R_1, R_2, ~\text{and}~R_3$$ give the correct voltages?
 1 $${R}_1=1~\text{k} \Omega, {R}_2=1 ~\text{k} \Omega, {R}_3=2 ~\text{k} \Omega$$ 2 $${R}_1=2 ~\text{k} \Omega, {R}_2=1~\text{k} \Omega, {R}_3=2~\text{k} \Omega$$ 3 $${R}_1=1 ~\text{k} \Omega, {R}_2=2~ \text{k} \Omega, {R}_3=2~ \text{k} \Omega$$ 4 $${R}_1=3~\text{k} \Omega, {R}_2=2~\text{k} \Omega, {R}_3=2~ \text{k} \Omega$$
Subtopic:  Combination of Resistors |
79%
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In the circuit shown in the figure, the effective resistance between $$A$$ and $$B$$ is:

1. $$2~\Omega$$
2. $$4~\Omega$$
3. $$6~\Omega$$
4. $$8~\Omega$$

Subtopic:  Combination of Resistors |
79%
From NCERT
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The effective resistance between points $$P$$ and $$Q$$ of the electrical circuit shown in the figure is:

 1 $$\frac{2 R r}{\left(R + r \right)}$$ 2 $$\frac{8R\left(R + r\right)}{\left( 3 R + r\right)}$$ 3 $$2r+4R$$ 4 $$\frac{5R}{2}+2r$$
Subtopic:  Combination of Resistors |
76%
From NCERT
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