# The drift velocity of free electrons in a conductor is $$v$$ when a current $$i$$ is flowing in it. If both the radius and current are doubled, then the drift velocity will be: 1. $$v$$ 2. $$\dfrac{v}{2}$$ 3. $$\dfrac{v}{4}$$ 4. $$\dfrac{v}{8}$$

Subtopic:  Current & Current Density |
72%
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A battery has emf $$4$$ V and internal resistance $$r$$. When this battery is connected to an external resistance of $$2$$ ohm, a current of $$1$$ ampere flows in the circuit. How much current will flow if the terminals of the battery are connected directly?
 1 $$1$$ A 2 $$2$$ A 3 $$4$$ A 4 Infinite
Subtopic:  EMF & Terminal Voltage |
66%
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The equivalent resistance between $$A$$ and $$B$$ is:

1. $$3~\Omega$$
2. $$6~\Omega$$
3. $$9~\Omega$$
4. $$12~\Omega$$

$\mathrm{}$

Subtopic:  Combination of Resistors |
72%
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The current $$I$$ as shown in the circuit will be:

 1 $$10~\text{A}$$ 2 $$\dfrac{20}{3}~\text{A}$$ 3 $$\dfrac{2}{3}~\text{A}$$ 4 $$\dfrac{5}{3}~\text{A}$$
Subtopic:  Combination of Resistors |
60%
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A meter bridge is set up to determine unknown resistance $$x$$ using a standard $$10~\Omega$$ resistor. The galvanometer shows the null point when the tapping key is at a $$52$$ cm mark. End corrections are $$1$$ cm and $$2$$ cm respectively for end $$A$$ and $$B$$. Then the value of $$x$$ is:

1. $$10.2~\Omega$$
2. $$10.6~\Omega$$
3. $$10.8~\Omega$$
4. $$11.1~\Omega$$

Subtopic:  Meter Bridge & Potentiometer |
52%
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The current through the $$5~\Omega$$ resistor is:

 1 $$3.2$$ A 2 $$2.8$$ A 3 $$0.8$$ A 4 $$0.2$$ A
Subtopic:  Kirchoff's Voltage Law |
68%
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The current in a wire varies with time according to the relation $$i = (3+2t)~\text{A}$$. The amount of charge passing a cross section of the wire in the time interval $$t=0$$ to $$t = 4.0~\text{s}$$  would be: (where $$t$$ is time in seconds)
 1 $$28$$ C 2 $$30.5$$ C 3 $$8$$ C 4 $$82$$ C
Subtopic:  Current & Current Density |
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In the circuit shown, the value of each of the resistances is $$r$$. The equivalent resistance of the circuit between terminals $$A$$ and $$B$$ will be:

 1 $$\dfrac{4r}{3}$$ 2 $$\dfrac{3r}{2}$$ 3 $$\dfrac{r}{3}$$ 4 $$\dfrac{8r}{7}$$
Subtopic:  Combination of Resistors |
69%
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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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If a metallic block has no potential difference applied across it, then the mean velocity of free electron is:
($$T$$= absolute temperature of the block)
 1 proportional to $$T$$. 2 proportional to$$\sqrt{T}$$ 3 zero. 4 finite but independent of temperature.
Subtopic:  Current & Current Density |
52%
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