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Q. No.The amount of charge \(Q\) passed in time \(t\) through a cross-section of a wire is \(Q=(7t^{2}+4t+1)~\text{C}.\) The value of current at time \(t= 6\) seconds is:
1. \( 38~ \text{A} \)
2. \( 27~ \text{A} \)
3. \( 104~ \text{A} \)
4. \( 88~ \text{A}\)
1. \( 38~ \text{A} \)
2. \( 27~ \text{A} \)
3. \( 104~ \text{A} \)
4. \( 88~ \text{A}\)
Subtopic: Current & Current Density |
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If \(n:\) number density of charge carriers.
\(A:\) cross-sectional area of the conductor
\(q:\) charge on each charge carrier
\(I:\) current through the conductor
Then the expression of drift velocity is:
1. \(\frac{nAq}{I}\)
2. \(\frac{I}{nAq}\)
3. \({nAqI}\)
4. \(\frac{IA}{nq}\)
\(A:\) cross-sectional area of the conductor
\(q:\) charge on each charge carrier
\(I:\) current through the conductor
Then the expression of drift velocity is:
1. \(\frac{nAq}{I}\)
2. \(\frac{I}{nAq}\)
3. \({nAqI}\)
4. \(\frac{IA}{nq}\)
Subtopic: Current & Current Density |
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The quantity represented by the drift velocity per unit electric field is:
| 1. | potential | 2. | resistivity |
| 3. | current | 4. | mobility |
Subtopic: Current & Current Density |
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Given below are two statements:
| Assertion (A): | As the drift velocity decreases, the current flowing through the conductor decreases. |
| Reason (R): | The current flowing through a conductor is directly proportional to the drift velocity. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
Subtopic: Current & Current Density |
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What will be the number of electrons passing through a heater wire in one minute, if it carries a current of \(4~\text{A}?\)
1. \(5 \times 10^{20}\)
2. \(4\times 10^{21}\)
3. \(15 \times 10^{20}\)
4. \(3 \times 10^{20}\)
1. \(5 \times 10^{20}\)
2. \(4\times 10^{21}\)
3. \(15 \times 10^{20}\)
4. \(3 \times 10^{20}\)
Subtopic: Current & Current Density |
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If electric current passing through a conductor varies with time as \(I=I_0+\beta t\) where \(I_0=20~\text{A}, \beta=3~\text{A/s},\) then the charge flows through the conductor in the first \(10\) sec is:
1. \(400~\text{C}\)
2. \(500~\text{C}\)
3. \(200~\text{C}\)
4. \(350~\text{C}\)
1. \(400~\text{C}\)
2. \(500~\text{C}\)
3. \(200~\text{C}\)
4. \(350~\text{C}\)
Subtopic: Current & Current Density |
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The SI unit of current density is:
| 1. | \(\text{A/m}^3\) | 2. | \(\text{A/m}^2\) |
| 3. | \(\text{A/m}\) | 4. | \(\text{A-m}\) |
Subtopic: Current & Current Density |
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When a current \(i\) flows through a conductor, the drift velocity of free electrons is \(v.\) If the current is increased to \(2i,\) and the cross-sectional area of the conductor is doubled, what will be the new drift velocity of the free electrons?
| 1. | \(\dfrac{v}{4}\) | 2. | \(\dfrac{v}{2}\) |
| 3. | \(v\) | 4. | \(4v\) |
Subtopic: Current & Current Density |
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Ammeter and voltmeter readings were recorded as \(0.5~\text{A}\) and \(1~\text{V}\) during the experiment to determine the resistance of a given wire using Ohm's law. The correct value of the resistance is:
1. \(1 ~\Omega\)
2. \(10.5~ \Omega\)
3. \(2 ~\Omega\)
4. \(4.5~ \Omega\)
1. \(1 ~\Omega\)
2. \(10.5~ \Omega\)
3. \(2 ~\Omega\)
4. \(4.5~ \Omega\)
Subtopic: Derivation of Ohm's Law |
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The Ohm's law for a metallic conductor can be represented by:
1. \(\frac{\text { potential difference }}{\text { current }}=\text{resistance} \)
2. \( \text{current} = \text{resistance} \times \text{potential difference} \)
3. \(\text{current} =\frac{\text { resistance }}{\text { potential difference }} \)
4. \(\text{Both}~ (2)~ \text{and} ~(3)\)
1. \(\frac{\text { potential difference }}{\text { current }}=\text{resistance} \)
2. \( \text{current} = \text{resistance} \times \text{potential difference} \)
3. \(\text{current} =\frac{\text { resistance }}{\text { potential difference }} \)
4. \(\text{Both}~ (2)~ \text{and} ~(3)\)
Subtopic: Derivation of Ohm's Law |
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