Current Electricity - CBSE STD 12 Science JEE physics Questions

Q 1Assertion & Reason1 Mark

Assertion : The resistivity of a semiconductor increases with temperature.
Reason : The atoms of a semiconductor vibrate with larger amplitude at higher temperatures thereby increasing its resistivity\

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Q 2Assertion & Reason1 Mark

Assertion : In a simple battery circuit the point of lowest potential is positive terminal of the battery
Reason : The current flows towards the point of the higher potential as it flows in such a circuit from the negative to the positive terminal.

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Q 3Assertion & Reason1 Mark

Assertion : The temperature coefficient of resistance is positive for metals and negative for $p$-type semiconductor.
Reason : The effective charge carriers in metals are negatively charged whereas in $p$-type semiconductor they are positively charged.

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Q 4Assertion & Reason1 Mark

Assertion : In the following circuit emf is $2 \mathrm{~V}$ and internal resistance of the cell is $1 \Omega$ and $R=1 \Omega$, then reading of the voltmeter is $1 V$.

Reason $\quad: V=E-i r$ where $E=2 V, i=\frac{2}{2}=1 A$ and $R=$ $1 \Omega$

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Q 5Assertion & Reason1 Mark

Assertion : There is no current in the metals in the absence of electric field.
Reason : Motion of free electron are randomly.

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Q 6MCQ1 Mark

The following four wires are made of the same material and are at the same temperature. Which one of them has highest electrical resistance

✓
Length $=50 \mathrm{~cm}$, diameter $=0.5 \mathrm{~mm}$
B
Length $=100 \mathrm{~cm}$, diameter $=1 \mathrm{~mm}$
C
Length $=200 \mathrm{~cm}$, diameter $=2 \mathrm{~mm}$
D
Length $=300 \mathrm{~cm}$, diameter $=3 \mathrm{~mm}$

Answer: A.

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Q 7MCQ1 Mark

A wire of diameter $0.02$ metre contains $10-$ free electrons per cubic metre. For an electrical current of $100 \mathring A$, the drift velocity of the free electrons in the wire is nearly

A
$1 \times 10^{-3} \mathrm{m} / \mathrm{s}$
B
$5 \times 10^{-6} \mathrm{m} / \mathrm{s}$
✓
$2 \times 10^{-4} . \mathrm{m} / \mathrm{s}$
D
$8 \times 10 \mathrm{~m} / \mathrm{s}$

Answer: C.

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Q 8MCQ1 Mark

A voltmeter essentially consists of

✓
A high resistance, in series with a galvanometer
B
A low resistance, in series with a galvanometer
C
A high resistance in parallel with a galvanometer
D
A low resistance in parallel with a galvanometer

Answer: A.

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Q 9MCQ1 Mark

At room temperature, copper has free electron density of $8.4 \times 10^{28}$ per $\mathrm{m}^3$. The copper conductor has a cross-section of 10. $m$ and carries a current of $5.4 \mathrm{~A}$. The electron drift velocity in copper is

A
$400 \mathrm{~m} / \mathrm{s}$
B
$0.4 \mathrm{~m} / \mathrm{s}$
✓
$0.4 \mathrm{~mm} / \mathrm{s}$
D
$72 \mathrm{~m} / \mathrm{s}$

Answer: C.

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Q 10MCQ1 Mark

A $36\ \Omega$ galvanometer is shunted by resistance of $4 \ \Omega$. The percentage of the total current, which passes through the galvanometer is

A
$8 \%$
B
$9 \%$
✓
$10 \%$
D
$91 \%$

Answer: C.

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Current Electricity question types

Current Electricity questions

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Current Electricity JEE physics - Current Electricity

Current Electricity question types

Current Electricity questions

Generate a Current Electricity paper free