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### Kurs: Fizyka - 10 klasa (Indie) > Rozdział 3

Lekcja 10: Prepare for CBSE board exam (w j. angielskim)# Electricity class 10: CBSE previous question paper problems

Prepare for class 10 CBSE exam using this analysis of the last 10 years’ question papers from the chapter Electricity. Explore common and important questions, with solutions.

Let's explore some of the main types of problems that appeared in the last ten years of CBSE board exams, arranged by subtopic.

Happy practicing!

## Electric current and circuit

**Type A. Definitions**

*Frequency of appearance:*

**Q1. What is an electric circuit? Distinguish between an open and a closed circuit.**

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**Type B. Applying the definitions of Coulomb and current**

*Frequency of appearance:*

**Q2. A current of**$10\text{}\text{A}$ flows through a conductor for two minutes.

**(**$\text{i}$ ) Calculate the amount of charge passed through any area of cross section of the conductor.

**(**$\text{ii}$ ) If the charge of an electron is $1.6\times {10}^{-19}\text{}\text{C}$ , then calculate the total number of electrons flowing.

[

Feeling stuck?

- Understand the concept better with this
**video**: Unit of charge (Coulombs)

## Electric potential and potential difference

**Type C. Relation between potential difference and work**

*Frequency of appearance:*

**Q3. (**$\text{a}$ ) Define the term 'volt'.

**(**$\text{b}$ ) State the relation between work, charge and potential difference for an electric circuit.

**Calculate the potential difference between the two terminals of a battery if**$100\text{}\text{J}$ of work is required to transfer $20\text{}\text{C}$ of charge from one terminal of the battery to the other.

[

Feeling stuck?

- Get more practice with this
**exercise**: Voltage and work - Understand the concept better with these
**videos**: ( ) Intro to potential difference (& voltage), ($\text{i}$ ) Solved example: Potential difference & work done$\text{ii}$

## Circuit diagram

**Type D. Drawing circuit elements and circuits**

*Frequency of appearance:*

**Q4. Draw a schematic diagram of an electric circuit consisting of a battery of two cells each of**$1.5\text{}\text{V}$ , $5\text{}\mathrm{\Omega}$ , $10\text{}\mathrm{\Omega}$ and $15\text{}\mathrm{\Omega}$ resistors and a plug key, all connected in series.

[

**Q5. Draw the symbols of commonly used components in electric circuit diagrams for**

**(**$\text{i}$ ) an electric cell

**(**$\text{ii}$ ) open plug key

**(**$\text{iii}$ ) wires crossing without connection

**(**$\text{iv}$ ) variable resistor

**(**$\text{v}$ ) battery

**(**$\text{vi}$ ) electric bulb

**(**$\text{vii}$ ) resistance.

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## Ohm's law

**Type E.**$V$ -$I$ graph and applying Ohm's law

*Frequency of appearance:*

**Q6. State Ohm's law. Draw a labelled circuit diagram to verify this law in the laboratory. If you draw a graph between the potential difference and current flowing through a metallic conductor, what kind of curve will you get? Explain how you would use this graph to determine the resistance of the conductor.**

[

Feeling stuck?

- Understand the concept better with these
**videos**: ( ) Introduction to circuits and Ohm's law, ($\text{i}$ ) Solved example: Ohms law, ($\text{ii}$ ) Ohm's law graph (verifying Ohm's law), ($\text{iii}$ ) Solved example: (Ohm's law graph).$\text{iv}$

## Factor on which the resistance of a conductor depends

**Type F. Word problems and numericals**

*Frequency of appearance:*

**Q7. (**$\text{a}$ ) List the factors on which the resistance of a conductor in the shape of a wire depends.

**(**$\text{b}$ ) Why are metals good conductors of electricity while glass is a bad conductor of electricity? Give reasons.

**(**$\text{c}$ ) Why are alloys commonly used in electrical heating devices? Give reason.

[

**Q8. The resistance of a wire of**$0.01\text{}\text{cm}$ radius is $10\text{}\mathrm{\Omega}$ . If the resistivity of the material of the wire is $50\times {10}^{-8}\text{}\mathrm{\Omega}\text{m}$ , find the length of the wire.

[

**Q9. Define resistance of a conductor. State the factors on which resistance of a conductor depends. Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.**

**Calculate the resistance of**$50\text{}\text{cm}$ length of wire of cross sectional area $0.01\text{}{\text{mm}}^{2}$ and of resistivity $5\times {10}^{-8}\text{}\mathrm{\Omega}\text{m}$ .

[

Feeling stuck?

- Understand the concept better with this
**video**: Resistivity and conductivity

## Resistance of system of resistors

**Type G. Calculating equivalent resistance and currents**

*Frequency of appearance:*

**Q10. Two resistors, of resistances**$5\text{}\mathrm{\Omega}$ and $10\text{}\mathrm{\Omega}$ respectively are to be connected to a battery of e.m.f. $6\text{}\text{V}$ so as to obtain

**(**$\text{i}$ ) minimum current flowing

**(**$\text{ii}$ ) maximum current flowing.

**(**$\text{a}$ )How will you connect the resistances in each case?

**(**$\text{b}$ ) Calculate the strength of the total current in the circuit in the two cases.

[

**Q11. Consider the following electric circuit.**

**(**$\text{i}$ ) Which two resistors are connected in series?

**(**$\text{ii}$ ) Which two resistors are connected in parallel?

**(**$\text{iii}$ ) If every resistor is $2\text{}\mathrm{\Omega}$ , what current will flow in the circuit?

[

**Type H. Derivations**

*Frequency of appearance:*

**Q12. Deduce the expression for the equivalent resistance of the parallel combination of three resistors**${\text{R}}_{1}$ , ${\text{R}}_{2}$ , and ${\text{R}}_{3}$ .

[

Feeling stuck?

- Get more practice with these
**exercises**: ( ) Finding equivalent resistance, ($\text{i}$ ) Identifying types of resistor combinations, ($\text{ii}$ ) Simplifying resistor networks, ($\text{iii}$ ) Finding currents and voltages (pure circuits).$\text{iv}$ - Understand the concept better with these
**videos**: ( ) Series resistors, ($\text{i}$ ) Parallel resistors (part 1), ($\text{ii}$ ) Parallel resistors (part 2), ($\text{iii}$ ) Parallel resistors (part 3), ($\text{iv}$ ) Example: Analyzing a more complex resistor circuit, ($\text{v}$ ) Solved example: Finding current & voltage in a circuit.$\text{vi}$

## Heating effect of electric current

**Type I. Relation between heat produced in a wire and resistance**

*Frequency of appearance:*

**Q13. A fuse wire melts at**$5\text{}\text{A}$ . If it is desired that the fuse wire of the same material melt at $10\text{}\text{A}$ , then should the new fuse wire be of smaller or larger radius than the earlier one? Give reasons for your answer.

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**J. Derivations and conceptual problems**

*Frequency of appearance:*

**Q14. Derive an expression for the heat produced in a conductor of resistance**$R$ when a current $I$ flows through it for some time $t$ .

**Two identical resistors of resistance**$R$ are connected in series with a battery of potential difference $V$ for time $t$ . The resistors are then connected in parallel with the same battery for the same time $t$ . Compare the heat produced in the two cases.

[

Feeling stuck?

- Get more practice with this
**exercise**: Calculating heat dissipated in circuits. - Understand the concept better with these
**videos**: ( ) Heating effect of current, ($\text{i}$ ) Solved example - Calculating power & heat dissipated.$\text{ii}$

## Electric power

**Type K. Calculating power and energy consumed**

*Frequency of appearance:*

**Q15. Two lamps, one rated**$100\text{}\text{W};\text{}220\text{}\text{V}$ , and the other $60\text{}\text{W};\text{}220\text{}\text{V}$ , are connected in parallel to electric mains supply. Find the current drawn by the two lamps from the line, if the supply voltage is $220\text{}\text{V}$ .

[

**Q16. (**$\text{a}$ ) How should two resistors, with resistances ${R}_{1}\text{}\mathrm{\Omega}$ and ${R}_{2}\text{}\mathrm{\Omega}$ be connected to a battery of e.m.f. $V$ volts so that the electrical power consumed is minimum?

**(**$\text{b}$ ) In a house, $3$ bulbs of $100$ watt each are lighted for $5$ hours daily, $2$ fans of $50$ watt each are used for $10$ hours daily and an electric heater of $1.00\text{}\text{kWh}$ is used for half an hour daily. Calculate the total energy consumed in a month of $31$ days and its cost at the rate of $\text{\u20b9}\text{3.60/kWh}$ .

[

Feeling stuck?

- Get more practice with this
**exercise**: Bulbs connected in series or parallel. - Understand the concept better with these
**videos**: ( ) Electric power & energy, ($\text{i}$ ) Solved example: Power dissipated in bulbs, ($\text{ii}$ ) Solved example - Cost of operation of electrical device.$\text{iii}$

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