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## Class 10 Physics (India)

### Course: Class 10 Physics (India)>Unit 3

Lesson 10: Summary

# 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.
[$2$ marks, AI $2009$]
Type B. Applying the definitions of Coulomb and current
Frequency of appearance: $★★★★★$
Q2. A current of 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 , then calculate the total number of electrons flowing.
[$3$ marks, Board Term I, $2013$]
Feeling stuck?

## 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 of work is required to transfer of charge from one terminal of the battery to the other.
[$3$ marks, AI $2009$]
Feeling stuck?

## 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 , , and resistors and a plug key, all connected in series.
[$1$ mark, AI $2009$]
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.
[$4$ marks, Board Term I $2017$]

## 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.
[$5$ marks, Board Term I, $2016$]
Feeling stuck?

## 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.
[$3$ marks, $2018$ (AI, Delhi, Foreign)]
Q8. The resistance of a wire of radius is . If the resistivity of the material of the wire is , find the length of the wire.
[$3$ marks, Board Term I, $2014$]
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 length of wire of cross sectional area and of resistivity .
[$5$ marks, Board Term I, $2009$]
Feeling stuck?

## Resistance of system of resistors

Type G. Calculating equivalent resistance and currents
Frequency of appearance: $★★★★★$
Q10. Two resistors, of resistances and respectively are to be connected to a battery of e.m.f. 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.
[$3$ marks, Delhi $2009$]
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 , what current will flow in the circuit?
[$3$ marks, Delhi $2009$]
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 ${\text{R}}_{3}$.
[$2$ marks, Foreign $2010$]
Feeling stuck?

## 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 . If it is desired that the fuse wire of the same material melt at , then should the new fuse wire be of smaller or larger radius than the earlier one? Give reasons for your answer.
[$3$ marks, Board Term I, $2014$]
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.
[$5$ marks, Foreign $2010$]
Feeling stuck?

## Electric power

Type K. Calculating power and energy consumed
Frequency of appearance: $★★★★★$
Q15. Two lamps, one rated , and the other , are connected in parallel to electric mains supply. Find the current drawn by the two lamps from the line, if the supply voltage is .
[$2$ marks, Board Term I, $2014$]
Q16. ($\text{a}$) How should two resistors, with resistances and 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 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 .
[$5$ marks, Board Term I, $2017$]
Feeling stuck?

## Want to join the conversation?

• What does it mean by resistor R1 is shorted and does not contribute to equivalent resistance in Q11] iii) solution?
• Hey Nandini

Take an example involving yourself - If you have an option of going to the same destination through a flat route as well as a steep hilly route, which one would you choose? Generally, the flat route - because it is easier

Current always flows through the easiest path it gets.
As you know, a resistor is something that opposes the flow of current. Hence, if the current finds a path with no resistor at a place, it would go through that instead of the path with the resistor. This is also called short-circuiting.

In Q)11 iii), you see that there is a wire with no resistor joining the same points which R1 does; the current rather flows through the non-resistor path. Here we say, R1 is shorted. Hence R1 has no impact on the current flowing through the circuit as no current is flowing through R1.

Hope it helps. Feel free to comment if your doubt persists...Have fun learning :)
• diffrentiate between joules and watt
• Joule is the SI Unit of Energy while Watt is the SI Unit of Power.
• Is this both electricity and its effects and magnetic effects of electric current, or one only?
(1 vote)
• Electric current can have 3 effects: (i)Heating Effect; (ii)Magnetic Effect & (iii)Chemical Effect
Thus, the magnetic effect of electric current is just one of electric current's effect
Hope it helps :)
• can you guys explain to me functions and the functioning of a fuse wire?
I love what you do at Khan Academy. Thank you for the unrelentless hard work you guys put it. Mad respect!