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Current Electric

This practice paper on Current Electricity consists of multiple sections, including MCQs, short answer questions, conceptual derivations, numericals, and long answer questions, totaling a maximum of 35 marks. It covers fundamental concepts such as drift velocity, Ohm's law, resistance, and circuit analysis. The paper is designed to test understanding and application of electrical principles in various scenarios.

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16 views2 pages

Current Electric

This practice paper on Current Electricity consists of multiple sections, including MCQs, short answer questions, conceptual derivations, numericals, and long answer questions, totaling a maximum of 35 marks. It covers fundamental concepts such as drift velocity, Ohm's law, resistance, and circuit analysis. The paper is designed to test understanding and application of electrical principles in various scenarios.

Uploaded by

Gitika English classes
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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📝 Current Electricity – Practice Paper

Maximum Marks: 35 Time: 1 hr 30 min

Section A: MCQs (1 mark each)

Q1. Drift velocity of electrons depends on:


(a) Relaxation time (b) Mobility (c) Electric field (d) All of these
Q2. If length of a conductor is doubled and area is halved, its resistance
becomes:
(a) 2R (b) 4R (c) R/2 (d) R/4
Q3. A wire of resistance R is cut into n equal parts and connected in parallel.
The equivalent resistance is:
(a) R/n (b) R/n² (c) R²/n (d) R
Q4. Which of the following is correct?
(a) Drift velocity ∝ current density
(b) Current ∝ potential gradient
(c) Resistivity depends on material and temperature only
(d) All of these
Q5. The slope of V–I graph of a conductor gives:
(a) Conductivity (b) Resistance (c) Resistivity (d) Reciprocal of resistance
Section B: Short Answer (2 marks each)

Q6. Define mobility of electrons. Derive its relation with drift velocity.
Q7. State and explain Ohm’s law. Under what conditions does it fail?
Q8. Write any two differences between resistance and resistivity.
Q9. Why is manganin used in making standard resistors ??
Q10. Explain why current is same in all elements connected in series.
Section C: Conceptual / Derivation (3 marks each)

Q11. Derive the expression for drift velocity in terms of current density.
Q12. State and derive the relation for effective resistance of resistors in
parallel.
Q13. A battery of emf E and internal resistance r is connected across a
resistor R. Derive expression for (i) current, (ii) terminal voltage.
Q14. Derive an expression for current density in terms of electric field and
conductivity.
Q15. Prove that power dissipated in a conductor is given by .

Section D: Numericals (4 marks each)

Q16. A copper wire of length 2 m and cross-sectional area 1 mm² has


resistivity . Calculate its resistance.
Q17. A current of 3 A flows through a resistor of 2 Ω. Find the heat produced in
2 minutes.
Q18. A cell of emf 2 V and internal resistance 0.5 Ω is connected to a resistor
of 9.5 Ω. Find the potential difference across the resistor and across the cell.
Q19. Find the equivalent resistance between A and B in a network where three
resistors 6 Ω, 6 Ω, and 3 Ω are connected in parallel.
Q20. A wire of resistance 10 Ω is stretched to double its length. Calculate its
new resistance and resistivity.

Section E: Long Answer / HOTs (5 marks each)


Q21. Derive the expression for the emf of a cell using the concept of internal
resistance. Show graphically the variation of terminal voltage with current.
Q22. Derive expression for the equivalent resistance of a Wheatstone bridge
in balanced condition.
Q23. A cell of emf 1.5 V and internal resistance 1 Ω is connected to a 9 Ω
resistor. Calculate (i) current (ii) terminal voltage (iii) power delivered to
external circuit and power dissipated inside cell.
Q24. Derive Ohm’s law microscopically using the concept of drift velocity and
relaxation time.
Q25. Two cells of emf 2 V and 4 V with internal resistances 1 Ω and 2 Ω are
connected in parallel. Find equivalent emf and internal resistance of the
combination.

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