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PHXII03:CURRENT ELECTRICITY

357005 Two identical conductors maintained at same temperatures are given potential difference in the ratio 1 : 2. The ratio of their drift velocities is

1

1 : 2

2

1 : 4

3

3 : 2

4

1 : 1

Explanation:

The drift speed $v_{d} = \frac{i}{n e A} = \frac{Δ V}{n e A R}$
$v_{d} \propto Δ V \Rightarrow \frac{v_{d_{1}}}{v_{d_{2}}} = \frac{Δ V_{1}}{Δ V_{2}} = \frac{1}{2}$

PHXII03:CURRENT ELECTRICITY

357006 When a current $I$ is set up in a wire of radius $r$ , the drift velocity is $v_{d}$ . If the same current is set up through a wire of radius $2 r$ , the drift velocity will be

1

4 v_{d}

2

2 v_{d}

3

v_{d} / 2

4

v_{d} / 4

Explanation:

$I = n A e v_{d} o r v_{d} \propto 1 / π r^{2}$
$\frac{v_{d_{1}}}{v_{d_{2}}} = {(\frac{r_{2}}{r_{1}})}^{2} = {(\frac{2 r}{r})}^{2} = 4$
$v_{d_{2}} = \frac{v_{d_{1}}}{4} = \frac{v_{d}}{4}$

PHXII03:CURRENT ELECTRICITY

357007 Assertion :
Though large number of free electrons are present in the metal, yet there is no current in the absence of electric field.
Reason :
In the absence of electric field, electrons move randomly in all directions.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

PHXII03:CURRENT ELECTRICITY

357008 Assertion :
The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.
Reason :
On increasing temperature, conductivity of metallic wire decreases.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

PHXII03:CURRENT ELECTRICITY

357005 Two identical conductors maintained at same temperatures are given potential difference in the ratio 1 : 2. The ratio of their drift velocities is

1

1 : 2

2

1 : 4

3

3 : 2

4

1 : 1

Explanation:

The drift speed $v_{d} = \frac{i}{n e A} = \frac{Δ V}{n e A R}$
$v_{d} \propto Δ V \Rightarrow \frac{v_{d_{1}}}{v_{d_{2}}} = \frac{Δ V_{1}}{Δ V_{2}} = \frac{1}{2}$

PHXII03:CURRENT ELECTRICITY

357006 When a current $I$ is set up in a wire of radius $r$ , the drift velocity is $v_{d}$ . If the same current is set up through a wire of radius $2 r$ , the drift velocity will be

1

4 v_{d}

2

2 v_{d}

3

v_{d} / 2

4

v_{d} / 4

Explanation:

$I = n A e v_{d} o r v_{d} \propto 1 / π r^{2}$
$\frac{v_{d_{1}}}{v_{d_{2}}} = {(\frac{r_{2}}{r_{1}})}^{2} = {(\frac{2 r}{r})}^{2} = 4$
$v_{d_{2}} = \frac{v_{d_{1}}}{4} = \frac{v_{d}}{4}$

PHXII03:CURRENT ELECTRICITY

357007 Assertion :
Though large number of free electrons are present in the metal, yet there is no current in the absence of electric field.
Reason :
In the absence of electric field, electrons move randomly in all directions.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

PHXII03:CURRENT ELECTRICITY

357008 Assertion :
The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.
Reason :
On increasing temperature, conductivity of metallic wire decreases.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

PHXII03:CURRENT ELECTRICITY

357005 Two identical conductors maintained at same temperatures are given potential difference in the ratio 1 : 2. The ratio of their drift velocities is

1

1 : 2

2

1 : 4

3

3 : 2

4

1 : 1

Explanation:

The drift speed $v_{d} = \frac{i}{n e A} = \frac{Δ V}{n e A R}$
$v_{d} \propto Δ V \Rightarrow \frac{v_{d_{1}}}{v_{d_{2}}} = \frac{Δ V_{1}}{Δ V_{2}} = \frac{1}{2}$

PHXII03:CURRENT ELECTRICITY

357006 When a current $I$ is set up in a wire of radius $r$ , the drift velocity is $v_{d}$ . If the same current is set up through a wire of radius $2 r$ , the drift velocity will be

1

4 v_{d}

2

2 v_{d}

3

v_{d} / 2

4

v_{d} / 4

Explanation:

$I = n A e v_{d} o r v_{d} \propto 1 / π r^{2}$
$\frac{v_{d_{1}}}{v_{d_{2}}} = {(\frac{r_{2}}{r_{1}})}^{2} = {(\frac{2 r}{r})}^{2} = 4$
$v_{d_{2}} = \frac{v_{d_{1}}}{4} = \frac{v_{d}}{4}$

PHXII03:CURRENT ELECTRICITY

357007 Assertion :
Though large number of free electrons are present in the metal, yet there is no current in the absence of electric field.
Reason :
In the absence of electric field, electrons move randomly in all directions.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

PHXII03:CURRENT ELECTRICITY

357008 Assertion :
The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.
Reason :
On increasing temperature, conductivity of metallic wire decreases.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

PHXII03:CURRENT ELECTRICITY

357005 Two identical conductors maintained at same temperatures are given potential difference in the ratio 1 : 2. The ratio of their drift velocities is

1

1 : 2

2

1 : 4

3

3 : 2

4

1 : 1

Explanation:

The drift speed $v_{d} = \frac{i}{n e A} = \frac{Δ V}{n e A R}$
$v_{d} \propto Δ V \Rightarrow \frac{v_{d_{1}}}{v_{d_{2}}} = \frac{Δ V_{1}}{Δ V_{2}} = \frac{1}{2}$

PHXII03:CURRENT ELECTRICITY

357006 When a current $I$ is set up in a wire of radius $r$ , the drift velocity is $v_{d}$ . If the same current is set up through a wire of radius $2 r$ , the drift velocity will be

1

4 v_{d}

2

2 v_{d}

3

v_{d} / 2

4

v_{d} / 4

Explanation:

$I = n A e v_{d} o r v_{d} \propto 1 / π r^{2}$
$\frac{v_{d_{1}}}{v_{d_{2}}} = {(\frac{r_{2}}{r_{1}})}^{2} = {(\frac{2 r}{r})}^{2} = 4$
$v_{d_{2}} = \frac{v_{d_{1}}}{4} = \frac{v_{d}}{4}$

PHXII03:CURRENT ELECTRICITY

357007 Assertion :
Though large number of free electrons are present in the metal, yet there is no current in the absence of electric field.
Reason :
In the absence of electric field, electrons move randomly in all directions.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

PHXII03:CURRENT ELECTRICITY

357008 Assertion :
The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.
Reason :
On increasing temperature, conductivity of metallic wire decreases.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

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