Table of contents
Previous Year Questions 2024
Q1: (A) Show how you would connect three resistors each of resistance 6 Ω, so that the combination has
a resistance of 9 Ω. Also, justify your answer.
OR
(B) In the given circuit calculate the power consumed in watts in the resistor of 2 Ω: (3 Marks) (2024)
View Answer
Q2: (A) (i) Define electric power. Express it in terms of potential difference (V) and resistance (R). (4 to 5
Marks) (2024)
(ii) An electric oven is designed to work on the mains voltage of 220 V. This oven consumes 11 units of
electrical energy in 5 hours. Calculate : (a) power rating of the oven (b) current drawn by the oven (c)
resistance of the oven when it is red hot
OR
(B) (i) Write the relation between resistance R and electrical resistivity p of the material of a conductor
in the shape of cylinder of length / and area of cross-section A. Hence derive the SI unit of electrical
resistivity.
(ii) The resistance of a metal wire of length 3 m is 60 Ω. If the area of the cross-section of the wire is 4 x
10-7 m, calculate the electrical resistivity of the wire.
(iii) State how would electrical resistivity be affected if the wire (of part ‘ii’) is stretched so that its length
is doubled. Justify your answer.
View Answer
Q3: Study the I-V graph for three resistors of resistances R1, R2 and R3 and select the correct statement
from the following: (1 Mark) (2024)
(a) R1 = R2 = R3
(b) R1 > R2 > R3
(c) R3 > R2 > R1
(d) R2 > R3 > R1
View Answer
Q4: Use Ohm’s law to determine the potential difference across the 3 Ω resistor in the circuit shown in
the following diagram when the key is closed. (2 Marks) (2024)
View Answer
Q5: In the case of four wires of the same material, the resistance will be minimum if the diameter and
length of the wire respectively are
(1 Mark) (2024)
(a) D/2 and L/4
(b) D/4 and 4L
(c) 2D and L
(d) 4D and 2L
View Answer
Q6: Explain in brief the function of an electric fuse in a domestic circuit. An electric heater of current
rating 3 kW; 220 V is to be operated in an electric circuit of rating 5 A. What is likely to happen when the
heater is switched ‘ON’ ? Justify your answer with the necessary calculation. (3 Marks) (CBSE 2024)
View Answer
Q7: (a) State Ohm’s law. Write the formula for the equivalent resistance R of the parallel combination of
three resistors of values R1, R2, and R3.
(b) Find the resistance of the following network of resistors: (3 Marks) (2024)
View Answer
Q8: Case/Source-based questions. (4 to 5 Marks) (CBSE 2024)
In a domestic circuit, five LED bulbs are arranged as shown. The source voltage is 220 V and the power
rating of each bulb is marked in the circuit diagram. Based on the following circuit diagram, answer the
following questions:
(a) State what happens when (i) key K1 is closed. (ii) key K2 is closed.
(b) Find the current drawn by the bulb B when it glows.
(c) Calculate (i) the resistance of bulb B, and (ii) the total resistance of the combination of four bulbs B,
C, D, and E.
OR
(c) What would happen to the glow of all the bulbs in the circuit when keys K1 and K2 both are closed
and the bulb C suddenly gets fused? Give a reason to justify your answer.
View Answer
Q9: Consider the following combinations of resistors: (1 Mark) (2024)
The combinations having equivalent resistance 1 is/are:
(a) I and IV
(b) Only IV
(c) I and II
(d) I, II and III
View Answer
Q10: An electric iron of resistance 20Ω draws a current of 5 A. The heat developed in the iron in 30
seconds is: (1 Mark) (2024)
(a) 15000 J
(b) 6000 J
(c) 1500 J
(d) 3000 J
View Answer
Q11: Two wires A and B of the same material, having the same lengths and diameters 0·2 mm and 0·3
mm respectively, are connected one by one in a circuit. Which one of these two wires will offer more
resistance to the flow of current in the circuit? Justify your answer. (1 Mark) (2024)
View Answer
Q12: The following questions are source-based/case-based questions. Read the case carefully and
answer the questions that follow.
Study the following circuit: (4 to 5 Marks) (2024)
On the basis of this circuit, answer the following questions:
(a) Find the value of total resistance between points A and B.
(b) Find the resistance between the points B and C.
(c) (i) Calculate the current drawn from the battery, when the key is closed.
OR
(c) (ii) In the above circuit, the 16 Ω resistor or the parallel combination of two resistors of 8 Ω, which
one of the two will have more potential difference across its two ends? Justify your answer.
View Answer
Q13: An electric source can supply a charge of 500 coulomb. If the current drawn by a device is 25 mA,
find the time in which the electric source will be discharged completely. (1 Mark) (2024)
View Answer
Q14: (a) (i) The potential difference across the two ends of a circuit component is decreased to one-third
of its initial value, while its resistance remains constant. What change will be observed in the current
flowing through it? Name and state the law which helps us to answer this question.
(ii) Draw a schematic diagram of a circuit consisting of a battery of four 1.5 V cells, a 5 Ω resistor, a 10 Ω
resistor and a 15 Ω resistor, and a plug key, all connected in series. Now find (I) the electric current
passing through the circuit, and (II) the potential difference across the 10 Ω resistor when the plug key is
closed.
OR
(b) (i) When is the potential difference between two points said to be 1 volt?
(ii) A copper wire has a diameter of 0.2 mm and resistivity of 1.6 x 10-8 Ω m. What will be the length of
this wire to make its resistance 14 Ω? How much does the resistance change if the diameter of the wire
is doubled? (4 to 5 Marks(2024)
View Answer
Q15: In the given circuit the total resistance between X and Y is:
(a) 12Ω
(b) 4 Ω
(c) 6 Ω
(d) 1 Ω (1 Mark) (CBSE 2024)
View Answer
Q16: Draw a schematic diagram of a circuit consisting of a battery of four dry cells of 1.5 V each, a 2 Ω
resistor, a 6 Ω resistor, a 16 Ω resistor and a plug key all connected in series. Put an ammeter to measure
the current in the circuit and a voltmeter across the 16 Ω resistor to measure the potential difference
across its two ends. Use Ohm’s law to determine:
(A) ammeter reading, and
(B) voltmeter reading when the key is closed. (3 Marks) (2024)
View Answer
Previous Year Questions 2023
Q1: The expressions that relate (i) Q, I and t and (ii) Q, V and W respectively are (here the symbols have
their usual meanings):
(1 Mark) (2023)
(a) (i) I = Q/t (ii) W = V/Q
(b) (i) Q = I × t (ii) W = V × Q
(c) (i) Q = I/t (ii) V = W/Q
(d) (i) I = Q/t (ii) Q = V/W
View Answer
Q2: (i) How is electric current related to the potential difference across the terminals of a conductor?
Draw the labelled circuit diagram to verify this relationship. (4 to 5 Marks) (2023)
(ii) Why should an ammeter have low resistance?
(iii) Two V-I graphs A and B for series and parallel combinations of two resistors are as shown.
Giving reason state which graph shows (a) series, (b) parallel combination of the resistors.
View Answer
Q3: (a) Define electric power and state its SI unit. The commercial unit of electrical energy is known as
'unit'. Write the relation between this 'unit' and joule. (5 Marks) (2023)
(b) In a house, 2 bulbs of 50 W each are used for 6 hours daily and an electric geyser of 1 kW is used for
1 hour daily. Calculate the total energy consumed in a month of 30 days and its cost at the rate of ₹ 8.00
per kWh.
View Answer
Q4: If four identical resistors, of resistance 8 ohms, are first connected in series so as to give an effective
resistance Rs, and then connected in parallel so as to give an effective resistance Rp, then the ratio RS /
RP is:
(a) 32
(b) 2
(c) 0.5
(d) 16 (1 Mark) (CBSE 2023)
View Answer
Q5: In the following diagram, the position of the needle is shown on the scale of a voltmeter. The least
count of the voltmeter and the reading shown by it respectively are:
(a) 0.15 V and 1.6 V
(b) 0.05 V and 1.6 V
(c) 0.15 V and 1.8 V
(d) 0.05 V and 1.8 V (1 Mark) (CBSE 2023)
View Answer
Q6: (A) An electric iron consumes energy at a rate of 880 W when the heating is at the maximum rate
and 330 W when the heating is at the minimum. If the source voltage is 220 V, calculate the current and
resistance in each case.
(B) What is the heating effect of electric current?
(C) Find an expression for the amount of heat produced when a current passes through a resistor for
some time. (4 to 5 Marks) (CBSE 2023)
View Answer
Previous Year Questions 2022
Q1: (a) State Ohm's Law. Represent it mathematically. (2022)
(b) Define 1 ohm.
(c) What is the resistance of a conductor through which a current of 0.5 A flows when a potential
difference of 2V is applied across its ends?
View Answer
Q2: In the following figure, three cylindrical conductors A, B and C are shown along with their lengths
and areas of cross-section.
If these three conductors are made of the same material and RA,RB, and RC be their respective
resistances, then find
(I) RA/RB, and (II)RA/RC . (2022)
View Answer
Q3: (a) List the factors on which the resistance of a uniform cylindrical conductor of a given material
depends.
(b) The resistance of a wire of 0.01 cm radius is 10Ω. If the resistivity of the wire is 50 x 10-8 Ω m, find
the length of this wire. (2022)
View Answer
Q4: Calculate the equivalent resistance of the following electric circuit: (2022)
View Answer
Q5: (i) Write the formula for determining the equivalent resistance between A and B of the two
combinations (I) and (II) of three resistors and arranged as follows:
(ii) If the equivalent resistance of the arrangements (I) and (II) are and respectively, then which one of
the following graphs is correctly labelled? Justify your answer. (2022)
View Answer
Q6: Study the following electric circuit in which the resistors are arranged in three arms A, B and C
(2022)
(a) Find the equivalent resistance of arm A.
(b) Calculate the equivalent resistance of the parallel combination of the arms B and C.
(c) (i) Determine the current that flows through the ammeter.
OR
(ii) Determine the current that flows in the ammeter when the arm B is withdrawn from the circuit
View Answer
Q7: (i) State Joule's law of heating. Express it mathematically when an appliance of resistance R is
connected to a source of voltage V and the current I flows through the appliance for a time t.
(ii) Α 5 Ω resistor is connected across a battery of 6 volts. Calculate the energy that dissipates as heat in
10 seconds. (2022)
View Answer
Q8: (a) Calculate the resistance of a metal wire of length 2 m and area of cross-section 1.55 × 10-6 m2
(Resistivity of the metal is 2.8 × 10-8 Ωm)
(b) Why are alloys preferred over pure metals to make the heating elements of electrical heating
devices? (2022)
View Answer
Q9: An electric heater rated 1100 W operates at 220 V. Calculate
(i) its resistance, and
(ii) the current drawn by it. (2022)
View Answer
Q10: (a) What is the meaning of electric power of an electrical device? Write its SI unit.
(b) An electric kettle of 2kW is used for 2 hours. Calculate the energy consumed in
(i) kilowatt-hour and
(ii) joules (2022)
View Answer
Q11: (i) Define electric power and write its SI unit.
(ii) Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to an
electric mains supply. What current is drawn from the line if the supply voltage is 220 V? (2022)
View Answer
Q12: Define the term electric power. An electric device of resistance R when connected across an
electric source of voltage V draws a current I. Derive an expression for the power in terms of resistance
R and voltage V. What is the power of a device of resistance 400 Ω operating at 200 V ? (2022)
View Answer
Previous Year Questions 2021
Q1: Two lamps one rated 100W at 220V, and the other 60W at 220V, are connected in parallel to
electric mains supply. What current is drawn from the line if the supply voltage is 220V? (2021)
View Answer
Previous Year Questions 2020
Q1: If a person has five resistors each of value 5Ω, then the maximum resistance he can obtain by
connecting them is (2020)
(a) 1Ω
(b) 5Ω
(c) 10Ω
(d) 25Ω
View Answer
Q2: The maximum resistance which can be made using four resistors each of resistance 2 Ω is (2020)
(a) 2 Ω
(b) 1 Ω
(c) 2.5 Ω
(d) 8 Ω
View Answer
Q3: The maximum resistance which can be made using four resistors each of resistance 1/2 Ω is (2020)
(a) 2Ω
(b) 1Ω
(c) 2.5Ω
(d) 8Ω
View Answer
Q4: A V-I graph for a nichrome wire is given below. What do you infer from this graph? Draw a labelled
circuit diagram to obtain such a graph. (2020)
View Answer
Q5: (a) Write the mathematical expression for Joule's law of heating.
(b) Compute the heat generated while transferring 96000 coulomb of charge in two hours through a
potential difference of 40 V. (2020)
View Answer
Q6: Two bulbs of 100 W and 40 W are connected in series. The current through the 100 W bulb is 1A.
The current through the 40 W bulb will be: (2020)
(a) 0.4A
(b) 0.6A
(c) 0.8A
(d) 1A
View Answer
Q7: (a) What is meant by the statement, "The resistance of a conductor is one ohm"?
(b) Define electric power. Write an expression relating electric power, potential difference and
resistance.
(c) How many 132 Ω resistors in parallel are required to carry 5 A on a 220 V line? (2020)
View Answer
Q8: (a) Write the mathematical expression for Joule's law of heating.
(b) Compute the heat generated while transferring 96000 coulombs of charge in two hours through a
potential difference of 40 V. (2020)
View Answer
Q9: A cylindrical conductor of length ‘l‘ and uniform area of cross-section ‘A‘ has resistance ‘R‘. Another
conductor of length 2.5l and resistance 0.5R and of the same material has area of cross-section:
(a) 5A
(b) 2.5A
(c) 0.5A
(d) 1 / 5A (CBSE 2020)
View Answer
Q10: The resistance of a resistor is reduced to half of its initial value. In doing so, if other parameters of
the circuit remain unchanged, the heating effects in the resistor will become:
(a) two times
(b) half
(c) one-fourth
(d) four times (CBSE 2020)
View Answer
Q11: Assertion (A): Alloys are commonly used in electrical heating devices like electric iron and heater.
Reason (R): Resistivity of an alloy is generally higher than that of its constituent metals but the alloys
have low melting points than their constitutent metals.
(a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true, and (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true. (CBSE 2020)
View Answer
Q12: Assertion (A): At high temperatures, metal wires have a greater chance of short circuiting.
Reason (R): Both resistance and resistivity of a material vary with temperature.
(a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true, and (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true. (CBSE 2020)
View Answer
Q13: (A) An electric bulb is rated at 200 V; 100 W. What is its resistance?
(B) Calculate the energy consumed by 3 such bulbs if they glow continuously for 10 hours for complete
month of November.
(C) Calculate the total cost if the rate is ₹ 6.50 per unit. (CBSE 2020)
View Answer
Previous Year Questions 2019
Q1: A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with
resistances R1, R2 and R3 respectively. Which of the following is true? (2019)
(a) R1 = R2 = R3
(b) R1 > R2 > R3
(c) R3 > R2 > R1
(d) R2 > R3 > R1
View Answer
Q2: When do we say that the potential difference between two points of a circuit in 1 volt? (2019)
View Answer
Q3: Define resistance. Give its SI unit. (2019)
View Answer
Q4: State ohm’s law. (2019)
View Answer
Q5: In the circuit given below, the resistors and have the values and respectively, which have been
connected to a battery of 12 V. Calculate
(a) the current through each resistor,(b) the total circuit resistance, and(c) the total current in the circuit.
(2019)
View Answer
Q6: On what factors does the resistance of a conductor depend?
Or
List the factors on which the resistance of a conductor in the shape of a wire depends. (2019)
View Answer
Q7: (a) A bulb is rated 40 W, 220 V. Find the current drawn by it when it is connected to a 220 V supply.
Also, find its resistance.
(b) If the given blub is replaced by a blub of rating 25 W, 220 V, will there be any change in the value of
current and resistance? Justify your answer and determine the change. (2019)
View Answer
Q8: Derive the expression for power P consumed by a device having resistance R and potential
difference V.
Or
A device of resistance R is connected across a source of V voltage and draws a current I . Derive an
expression for power in terms of voltage (or current) and resistance. (2019)
View Answer
Q9: Compare the power used in 2 Ω resistor in each of the following circuits shown in Fig. (a) and (b)
respectively. (2019)
View Answer
Q10: Derive the relation R = R1 + R2 + R3 when resistors are joined in series. (2019)
View Answer
Q11: (a) Write the relation between resistance and electrical resistivity of the material of a conductor in
the shape of a cylinder of length 'l' and area of cross-section 'A' Hence derive the SI unit of electrical
resistivity.
(b) Resistance of a metal wire of length 5 m is 100 Ω. If the area of cross-section of the wire is 3 x 10-7
m2, calculate the resistivity of the material. (2019)
View Answer
Q12: (a) With the help of a suitable circuit diagram prove that the reciprocal of the equivalent resistance
of a group of resistors joined in parallel is equal to the sum of the reciprocals of the individual
resistances.
(b) In an electric circuit two resistors of 12Ω each are joined in parallel to a 6 V battery. Find the current
drawn from the battery. (2019)
View Answer
Q13: Study the circuit of Fig. and find out : (i) Current in 12 Ω, resistor (ii) difference in the readings of A1
and A2 if any. (2019)
View Answer
Q14: (i) Draw a schematic diagram of a circuit consisting of a battery of five 2 V cells, a 5 Ω resistor, a 10
Ω resistor and a 15 Ω resistor and a plug key all connected in series.
(ii) Calculate the electric current passing through the above circuit when the key is closed. (iii) Potential
difference across 15 Ω resistor. (2019)
View Answer
Q15: An electric lamp of resistance 20 Ω and a conductor of resistance 4 Ω are connected to a 6 V
battery as shown in the circuit. Calculate
(а) the total resistance of the circuit,
(b) the current through the circuit,
(c) the potential difference across the (i) electric, lamp and (ii) conductor, and
(d) power of the lamp. (2019)
View Answer
Q16: (a) Three resistors R1, R2 and R3 are connected in parallel and the combination is connected to a
battery, ammeter, voltmeter and key. Draw suitable circuit diagram and obtain an expression for the
equivalent resistance of the combination of the resistors.
(b) Calculate the equivalent resistance of the network shown in Fig. (2019)
View Answer
Q17: (a) Three resistors o f resistances R1, R2 and R3 are connected in (i) series, and (ii) parallel. Write
expression for the equivalent resistance of the combination in each case.
(b) Two identical resistances of 12 Ω each are connected to a battery of 3 V.
Calculate the ratio of the power consumed by the resulting combinations with minimum resistance and
maximum resistance. (2019)
View Answer
Q18: Experimentally prove that in series combination of three resistances:
(а) current flowing through each resistance is same, and
(b) total potential difference is equal to the stun of potential differences across individual resistors.
(2019)
View Answer
Q19: Unit of electric power may also be expressed as:
(a) volt-ampere
(b) kilowatt-hour
(c) watt-second
(d) joule-second (CBSE 2019)
View Answer
Q20: When a 4 V battery is connected across an unknown resistor there is a current of 100 mA in the
circuit. The value of the resistance of the resistor is:
(a) 4 Ω
(b) 40 Ω
(c) 400 Ω
(d) 0.4 Ω (CBSE 2019)
View Answer
Q21: (A) In a given ammeter, a student saw that needle indicates 12th division in ammeter while
performing an experiment to verify Ohm’s law. If ammeter has 10 divisions between 0 to 0·5 A, then
what is the ammeter reading corresponding to 12th division?
(B) How do you connect an ammeter and a voltmeter in an electric circuit? (CBSE 2019)
View Answer
Previous Year Questions 2018
Q1: Show how would you join three resistors, each of resistance 9 Ω so that the equivalent resistance of
the combination is (i) 13.5 Ω, (ii) 6 Ω? (2018)
View Answer
Q2: State Joule’s law of heating. (2018)
View Answer
Q3: Why are metals good conductors of electricity whereas glass is a bad conductor of electricity? Give
reason. (2018)
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Previous Year Questions 2017
Q1: Nichrome is used to make the element of an electric heater. Why? (2017)
View Answer
Q2: Derive the relation when resistors are joined in parallel. (2017)
View Answer
Previous Year Questions 2016
Q1: Why do electricians wear rubber hand gloves while working? (2016)
View Answer
Q2: How are two resistors with resistances R1Ω and R2Ω are to be connected to a battery of emf 3 volts
to obtain maximum current flowing through it? (2016)
View Answer
Q3: What potential difference is needed to send a current of 5 A through the electrical appliance having
a resistance of 18 Ω? (2016)
View Answer
Q4: Power of a lamp is 60 W. Find the energy in SI unit consumed by it in 1 s. (2016)
View Answer
Q5: (a) What do you mean by the resistance of a conductor? Define its unit.
(b) In an electric circuit with a resistance wire and a cell, the current flowing is I. What would happen to
this current if the wire is replaced by another thicker wire of the same material and the same length?
Give reason. (2016)
View Answer
Q6: (a) Why are electric bulbs filled with chemically inactive nitrogen or argon gas?
(b) The resistance of a wire of 0.01 cm radius is 10 Ω. If the resistivity of the material of the wire is 50 x
10-8 Ω-m, find the length of the wire. (2016)
View Answer
Q7: (a) Define electric power. Express it in terms of V, I and R where V stands for potential difference, R
for resistance and I for current.
(b) V -I graphs for two wires A and B are shown in the Fig. 12.34. Both of them are connected in series to
a battery. Which of the two will produce more heat per unit time? Give justification for your answer.
(2016)
View Answer
Q8: (a) Establish a relationship to determine the equivalent resistance IS of a combination of three
resistors having resistances R1, R2 and R3 connected in parallel.
(b) Three resistors are connected in an electrical circuit as shown. Calculate the resistance between A
and B. (2016)
View Answer
Q9: (a) Establish a relationship to determine the equivalent resistance R of a combination of three
resistors having resistances R1, R2 and R3 connected in series.
(b) Calculate the equivalent resistance R of a combination of three resistors of 2 Ω, 3 Ω and 6 Ω joined in
parallel. (2016)
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Previous Year Questions 2015
Q1: Identify the following symbols of commonly used components in a circuit diagram: (2015)
View Answer
Q2: Define electric current. (2015)
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Q3: State the SI unit of electric current and define it. (2015)
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Q4: In an electric circuit, state the relationship between the direction of conventional current and the
direction of flow of electrons. (2015)
View Answer
Q5: What is meant by the statement "potential difference between points A and B in an electric field is 1
volt”? (2015)
View Answer
Q6: Define kW h. (2015)
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Q7: How many joules are equals to 1 kW h? (2015)
View Answer
Q8: Define an electric circuit. Draw a labelled, schematic diagram of an electric circuit comprising of a
cell, a resistor, an ammeter, a voltmeter and a closed switch. Distinguish between an open and a closed
circuit. (2015)
View Answer
Q9: (a) n electrons, each carrying a charge -e, are flowing across a unit cross section of a metallic wire in
unit time from east to west. Write an expression for electric current and also give its direction of flow.
Give reason for your answer.
(b) The charge possessed by an electron is 1.6 x 10-19 coulomb. Find the number of electrons that will
flow per second to constitute a current of 1 ampere. (2015)
View Answer
Q10: (a) List the factors on which the resistance of a cylindrical conductor depends and hence write an
expression for its resistance.
(b) How will the resistivity of a conductor change when its length is tripled by stretching it? (2015)
View Answer
Q11: (a) V-I graphs for two wires A and B are shown in the Fig. If both the wires are made of same
material and are of same length, which of the two is thicker? Give justification for your answer.
(b) A wire of length L and resistance R is stretched so that the length is doubled and area of cross-section
halved.
How will (i) resistance change, and (ii) resistivity change? (2015)
View Answer
Q12: Study the electric circuit of Fig. and find (i) the current flowing in the circuit, and (ii) the potential
difference across 10 Ω resistor. (2015)
View Answer
Q13: Three resistors of 3 Ω each are connected to a battery of 3 V as shown in Fig Calculate the current
drawn from the battery. (2015)
View Answer
Q14: A 5 Ω resistor is connected across a battery of 6 volts. Calculate:
(i) the current flowing through the resistor.
(ii) the energy that dissipates as heat in 10 s. (2015)
View Answer
Q15: Calculate the amount of heat generated while transferring 90000 coulombs of charge between the
two terminals of a battery of 40 V in one hour. Also determine the power expended in the process.
(2015)
View Answer
Q16: How many 40 W; 220 V lamps can be safely connected to a 220 V, 5 A line?
Justify your answer. (2015)
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Q17: What is meant by electric current ? Name and define its SI unit. In a conductor electrons are
flowing from B to A. What is the direction of conventional current ? Give justification for your answer.
A steady current of 1 ampere flows through a conductor. Calculate the number of electrons that flow
through any section of the conductor in 1 second.
(Charge on electron — 1.6 x 10-19 coulomb) (2015)
View Answer
Q18: What is heating effect of electric current ? Find an expression for amount of heat produced. Name
some appliances based on heating effect of current. (2015)
View Answer
Q19: What is the minimum resistance which can be made using five resistors, each of 1 / 5Ω?
(a) 1 / 5Ω
(b) 1 / 25Ω
(c) 1 / 10Ω
(d) 25Ω (CBSE 2015, 13, 12)
View Answer
Previous Year Questions 2014
Q1: Should the resistance of an ammeter be low or high? Give reason. (CBSE 2014)
View Answer
