1. MCQs — Multiple Choice Questions

A. Electric Current & Circuit

1. Electric current represents the rate of flow of:
A. Energy
B. Charge
C. Resistance
D. Potential
Answer: B

2. The SI unit of electric current is:
A. Volt
B. Ohm
C. Ampere
D. Watt
Answer: C

3. If $Q$Q charge flows through a conductor in time $t$t, current is:
A. $Qt$Qt
B. $Q/t$Q/t
C. $t/Q$t/Q
D. $Q+t$Q+t
Answer: B

4. Conventional current flows in a direction:
A. Same as electron flow
B. Opposite to electron flow
C. Perpendicular to electron flow
D. Randomly
Answer: B

5. A complete conducting path through which current can flow is called:
A. Resistance
B. Electric circuit
C. Battery
D. Potential
Answer: B

6. An ammeter is connected in:
A. Parallel
B. Series
C. Either series or parallel
D. Neither
Answer: B

7. One ampere is equal to:
A. $1\,J/C$1J/C
B. $1\,C/s$1C/s
C. $1\,V/A$1V/A
D. $1\,W/s$1W/s
Answer: B

8. A current of $2\,A$2A flowing for $5\,s$5s transfers a charge of:
A. $2.5\,C$2.5C
B. $7\,C$7C
C. $10\,C$10C
D. $25\,C$25C
Answer: C

---

B. Potential Difference

9. Potential difference is defined as work done per unit:
A. Time
B. Current
C. Charge
D. Resistance
Answer: C

10. The SI unit of potential difference is:
A. Ampere
B. Volt
C. Ohm
D. Joule
Answer: B

11. A voltmeter is connected:
A. In series
B. In parallel
C. In either arrangement
D. Only with a battery
Answer: B

12. The potential difference across a conductor is $12\,V$12V. If $2\,C$2C charge moves through it, the work done is:
A. $6\,J$6J
B. $10\,J$10J
C. $24\,J$24J
D. $36\,J$36J
Answer: C

---

C. Ohm’s Law

13. Ohm’s law is expressed as:
A. $V=I/R$V=I/R
B. $V=IR$V=IR
C. $R=VI$R=VI
D. $I=VR$I=VR
Answer: B

14. According to Ohm’s law, $V/I$V/I is:
A. Current
B. Charge
C. Resistance
D. Power
Answer: C

15. Ohm’s law is applicable when the temperature of the conductor:
A. Increases continuously
B. Decreases continuously
C. Remains constant
D. Becomes zero
Answer: C

16. The SI unit of resistance is:
A. Volt
B. Watt
C. Ohm
D. Ampere
Answer: C

17. If the voltage across a constant resistance is doubled, the current becomes:
A. Half
B. Double
C. Four times
D. Unchanged
Answer: B

18. If resistance is doubled while voltage remains constant, current becomes:
A. Double
B. Four times
C. Half
D. Unchanged
Answer: C

---

D. Resistance & Resistivity

19. Resistance of a uniform wire increases when its:
A. Length decreases
B. Length increases
C. Area increases
D. Resistivity decreases
Answer: B

20. For a uniform conductor, resistance is inversely proportional to its:
A. Length
B. Resistivity
C. Area of cross-section
D. Temperature only
Answer: C

21. The correct relation is:
A. $R=\rho Al$R=ρAl
B. $R=\rho A/l$R=ρA/l
C. $R=\rho l/A$R=ρl/A
D. $R=l/\rho A$R=l/ρA
Answer: C

22. The SI unit of resistivity is:
A. $\Omega$Ω
B. $\Omega m$Ωm
C. $V/m$V/m
D. $A/m$A/m
Answer: B

23. A thicker wire of the same material and length generally has:
A. Greater resistance
B. Smaller resistance
C. Infinite resistance
D. The same resistance in every case
Answer: B

24. Which is generally a good conductor?
A. Glass
B. Rubber
C. Copper
D. Ebonite
Answer: C

25. Which material is commonly used for bulb filaments?
A. Copper
B. Aluminium
C. Tungsten
D. Rubber
Answer: C

---

E. Series & Parallel

26. In a series combination, the current through each resistor is:
A. Different
B. Zero
C. The same
D. Infinite
Answer: C

27. Equivalent resistance of resistors in series is:
A. Their sum
B. Their difference
C. Always zero
D. Less than every resistor
Answer: A

28. In parallel combination, the potential difference across each branch is:
A. Different
B. The same
C. Zero
D. Infinite
Answer: B

29. For resistors in parallel, total current is:
A. The difference of branch currents
B. The product of branch currents
C. The sum of branch currents
D. Always zero
Answer: C

30. Equivalent resistance of a parallel combination is generally:
A. Greater than the largest resistance
B. Equal to the sum
C. Less than the smallest resistance
D. Infinite
Answer: C

31. Domestic electrical appliances are generally connected in:
A. Series
B. Parallel
C. Only mixed circuits
D. Open circuits
Answer: B

32. If one appliance fails in a parallel arrangement, other branches can generally:
A. Continue operating
B. Always stop
C. Become short circuits
D. Lose all resistance
Answer: A

---

F. Heating Effect

33. The heating effect of current is represented by:
A. $H=VIt$H=VIt
B. $H=V/I$H=V/I
C. $H=IR$H=IR
D. $H=Q/t$H=Q/t
Answer: A

34. Joule’s law of heating gives:
A. $H=I^2Rt$H=I2Rt
B. $H=IR/t$H=IR/t
C. $H=V/R$H=V/R
D. $H=R/It$H=R/It
Answer: A

35. For constant resistance and time, heat produced is proportional to:
A. $I$I
B. $I^2$I2
C. $1/I$1/I
D. $I^3$I3
Answer: B

36. An electric iron works mainly using the:
A. Magnetic effect
B. Heating effect
C. Chemical effect
D. Cooling effect
Answer: B

37. An electric fuse protects a circuit by:
A. Increasing voltage
B. Increasing resistance permanently
C. Breaking the circuit when excessive current flows
D. Producing more current
Answer: C

---

G. Electric Power & Energy

38. Electric power is given by:
A. $P=VI$P=VI
B. $P=V/I$P=V/I
C. $P=IR$P=IR
D. $P=Q/t$P=Q/t
Answer: A

39. Another expression for power is:
A. $I^2R$I2R
B. $IR^2$IR2
C. $V/R^2$V/R2
D. $R/V$R/V
Answer: A

40. The SI unit of electric power is:
A. Joule
B. Watt
C. Volt
D. Coulomb
Answer: B

41. Commercial electrical energy is measured in:
A. Watt
B. Joule/second
C. Kilowatt-hour
D. Ampere
Answer: C

42. One unit of electrical energy is equal to:
A. $3.6\times10^3\,J$3.6×103J
B. $3.6\times10^6\,J$3.6×106J
C. $36\times10^6\,J$36×106J
D. $360\,J$360J
Answer: B

---

2. Fill in the Blanks

1. The rate of flow of electric charge is called __________.
   Answer: electric current
2. The SI unit of current is __________.
   Answer: ampere
3. Conventional current is considered to flow opposite to the direction of __________.
   Answer: electron flow
4. A continuous closed path for current is called an __________.
   Answer: electric circuit
5. An ammeter is connected in __________ with the circuit.
   Answer: series
6. Potential difference is measured using a __________.
   Answer: voltmeter
7. A voltmeter is connected in __________.
   Answer: parallel
8. The SI unit of potential difference is __________.
   Answer: volt
9. Ohm’s law is represented by $V=$V= __________.
   Answer: $IR$IR
10. The SI unit of resistance is __________.
    Answer: ohm
11. Resistance is directly proportional to the __________ of a uniform wire.
    Answer: length
12. Resistance is inversely proportional to the __________ of cross-section.
    Answer: area
13. The symbol for resistivity is __________.
    Answer: $\rho$ρ
14. The SI unit of resistivity is __________.
    Answer: $\Omega m$Ωm
15. In a series circuit, the current is __________ through every resistor.
    Answer: the same
16. In a parallel circuit, the potential difference is __________ across each branch.
    Answer: the same
17. The equivalent resistance of resistors in series is the __________ of their individual resistances.
    Answer: sum
18. The heating effect of current is described by __________ law.
    Answer: Joule’s
19. Heat produced in a resistor is $H=$H= __________.
    Answer: $I^2Rt$I2Rt
20. Electric power is given by $P=$P= __________.
    Answer: $VI$VI
21. The SI unit of electric power is __________.
    Answer: watt
22. The commercial unit of electrical energy is __________.
    Answer: kilowatt-hour
23. One kilowatt-hour equals __________ joules.
    Answer: $3.6\times10^6$3.6×106
24. A fuse is connected in __________ with the appliance.
    Answer: series
25. Tungsten is commonly used for electric bulb __________.
    Answer: filaments

---

3. True or False

1. Electric current is the rate of flow of charge.
   True
2. An ammeter is connected in parallel.
   False
3. A voltmeter is connected in parallel.
   True
4. Conventional current is taken in the direction of electron flow.
   False
5. Resistance is measured in ohms.
   True
6. Resistance of a uniform wire increases with its length.
   True
7. Resistance increases when the cross-sectional area increases, all else being equal.
   False
8. Ohm’s law requires the temperature to remain constant.
   True
9. Current is the same through all resistors in series.
   True
10. Voltage is the same across parallel branches.
    True
11. Equivalent resistance in series is less than each individual resistance.
    False
12. Equivalent resistance in parallel is less than the smallest individual resistance.
    True
13. Domestic appliances are generally connected in series.
    False
14. Heating effect of current is used in electric heaters.
    True
15. A fuse is used to protect an electrical circuit.
    True
16. Electric power is measured in joules.
    False
17. Watt is the SI unit of power.
    True
18. One kWh equals $3.6\times10^6J$3.6×106J.
    True
19. Copper has a higher resistivity than rubber.
    False
20. A rheostat can be used to vary resistance in a circuit.
    True

---

4. Match the Following

Column A	Column B
1. Current	a. Watt
2. Potential difference	b. Ohm
3. Resistance	c. Ampere
4. Power	d. Volt
5. Resistivity	e. $\Omega m$Ωm
6. Electrical energy	f. kWh

Answers:
1–c, 2–d, 3–b, 4–a, 5–e, 6–f

---

5. Assertion–Reason Questions

Choose:

A. Both A and R are true, and R correctly explains A.
B. Both A and R are true, but R does not correctly explain A.
C. A is true, but R is false.
D. A is false, but R is true.

1. Assertion: A voltmeter is connected in parallel.
Reason: It measures potential difference between two points.
Answer: A

2. Assertion: A thicker wire generally has lower resistance than a thinner wire of the same material and length.
Reason: Resistance is inversely proportional to cross-sectional area.
Answer: A

3. Assertion: Current is the same through each resistor in a series circuit.
Reason: There is only one continuous path for charge flow.
Answer: A

4. Assertion: Domestic appliances are connected in parallel.
Reason: Parallel branches can have the same supply potential difference and operate independently.
Answer: A

5. Assertion: Increasing resistance at constant voltage decreases current.
Reason: $I=V/R$I=V/R.
Answer: A

6. Assertion: A fuse is connected in parallel with an appliance.
Reason: A fuse protects a circuit against excessive current.
Answer: D

7. Assertion: Heat produced is proportional to $I^2$I2 when resistance and time are constant.
Reason: $H=I^2Rt$H=I2Rt.
Answer: A

8. Assertion: The equivalent resistance of a parallel combination is less than the smallest individual resistance.
Reason: The total current divides among parallel branches.
Answer: A

---

6. Very Short Answer Questions

1. What is electric current?
2. Write the SI unit of current.
3. What is one ampere?
4. What is an electric circuit?
5. What is conventional current?
6. What is potential difference?
7. State the SI unit of potential difference.
8. Name the instrument used to measure current.
9. Name the instrument used to measure potential difference.
10. How is an ammeter connected?
11. How is a voltmeter connected?
12. State Ohm’s law.
13. Define resistance.
14. What is the SI unit of resistance?
15. What is resistivity?
16. State the SI unit of resistivity.
17. Name two factors affecting resistance.
18. What happens to resistance when the length of a wire is doubled?
19. What happens to resistance when the area of cross-section increases?
20. What is a rheostat?
21. What is meant by series combination?
22. What is meant by parallel combination?
23. State the current rule for series resistors.
24. State the voltage rule for parallel resistors.
25. What is Joule heating?
26. State Joule’s law of heating.
27. What is electric power?
28. State the SI unit of power.
29. What is the commercial unit of electrical energy?
30. What is the function of a fuse?

---

7. Short Answer Questions

1. Explain why a closed circuit is necessary for current to flow.
2. Differentiate between electron flow and conventional current direction.
3. Explain the role of a cell or battery in an electric circuit.
4. Why is an ammeter connected in series?
5. Why is a voltmeter connected in parallel?
6. Explain Ohm’s law and state the condition under which it applies.
7. How does the resistance of a wire depend on its length and cross-sectional area?
8. Why does a thicker wire generally offer less resistance than a thinner wire of the same material and length?
9. What is resistivity? How is it different from resistance?
10. Explain why alloys are useful in electrical heating devices.
11. Why is tungsten suitable for electric bulb filaments?
12. State the important characteristics of a series combination of resistors.
13. State the important characteristics of a parallel combination of resistors.
14. Give two disadvantages of connecting domestic appliances in series.
15. Give reasons why domestic appliances are connected in parallel.
16. Explain the heating effect of electric current.
17. State the factors on which heat produced in a resistor depends.
18. Explain the working principle of an electric fuse.
19. What is electric power? Write its three mathematical forms.
20. Explain the meaning of one kilowatt-hour.

---

8. Long Answer Questions

1. Explain electric current, potential difference and resistance. Write their SI units and important formulae.

2. State and explain Ohm’s law. Derive the relation $V=IR$V=IR and explain the meaning of resistance.

3. Explain the factors affecting resistance of a conductor and derive the relation:$$R=\rho\frac{l}{A}$$R=ρAl​

4. Explain resistors connected in series. Derive the expression:$$R_s=R_1+R_2+R_3$$Rs​=R1​+R2​+R3​

5. Explain resistors connected in parallel. Derive:$$\frac1{R_p} = \frac1{R_1} + \frac1{R_2} + \frac1{R_3}$$Rp​1​=R1​1​+R2​1​+R3​1​

6. Compare series and parallel combinations of resistors with respect to current, voltage and equivalent resistance.

7. Explain the heating effect of electric current and derive:$$H=I^2Rt$$H=I2Rt

8. Explain the construction and purpose of an electric fuse.

9. Explain electric power and derive:$$P=VI=I^2R=\frac{V^2}{R}$$P=VI=I2R=RV2​

10. Explain electrical energy and the commercial unit of electrical energy. Establish the relation:$$1\,kWh=3.6\times10^6J$$1kWh=3.6×106J

---

9. Numerical Questions

Level 1 — Basic

1. A charge of $240\,C$240C passes through a conductor in $2$2 minutes. Calculate the current.

2. A current of $0.5\,A$0.5A flows for $10$10 minutes. Find the charge transferred.

3. A charge of $5\,C$5C is moved through a potential difference of $12\,V$12V. Calculate the work done.

4. A resistor has a potential difference of $20\,V$20V across it and carries $4\,A$4A current. Find its resistance.

5. A $10\,\Omega$10Ω resistor is connected to a $20\,V$20V source. Calculate the current.

---

Level 2 — Resistance

6. A conductor has resistance $8\,\Omega$8Ω when connected to a $24\,V$24V source. Find the current.

7. A wire has resistance $10\,\Omega$10Ω. If its length is doubled without changing its material or cross-sectional area, what happens to its resistance?

8. A wire’s cross-sectional area is doubled while its length and material remain unchanged. How does its resistance change?

9. A wire of length $2\,m$2m and area $4\times10^{-6}m^2$4×10−6m2 has resistance $3\,\Omega$3Ω. Find its resistivity.

10. A wire has resistance $20\,\Omega$20Ω, length $4\,m$4m, and cross-sectional area $2\times10^{-6}m^2$2×10−6m2. Calculate its resistivity.

---

Level 3 — Series

11. Three resistors of $2\,\Omega$2Ω, $4\,\Omega$4Ω, and $6\,\Omega$6Ω are connected in series. Find their equivalent resistance.

12. A $5\,\Omega$5Ω and $15\,\Omega$15Ω resistor are connected in series to a $20\,V$20V source. Find the current.

13. Resistors of $3\,\Omega$3Ω, $5\,\Omega$5Ω, and $7\,\Omega$7Ω are connected in series to a $30\,V$30V source. Find:

• total resistance
• current
• potential difference across each resistor.

---

Level 4 — Parallel

14. Two resistors of $6\,\Omega$6Ω and $3\,\Omega$3Ω are connected in parallel. Calculate their equivalent resistance.

15. Resistors of $5\,\Omega$5Ω, $10\,\Omega$10Ω, and $20\,\Omega$20Ω are connected in parallel across $10\,V$10V. Find the current in each branch and total current.

16. Two resistors of $4\,\Omega$4Ω and $12\,\Omega$12Ω are connected in parallel across a $24\,V$24V supply. Calculate:

• current through each resistor
• total current
• equivalent resistance.

---

Level 5 — Heating & Power

17. A current of $5\,A$5A passes through a $4\,\Omega$4Ω resistor for $10\,s$10s. Calculate the heat produced.

18. A $100\,\Omega$100Ω appliance operates at $200\,V$200V. Find its power.

19. An appliance uses $2\,A$2A current at $220\,V$220V. Calculate its power.

20. A $1000\,W$1000W appliance operates for $3\,h$3h. Find the electrical energy consumed in kWh.

21. A $400\,W$400W appliance operates for $5\,h$5h every day for $30$30 days. Calculate the energy consumed in kWh.

22. An appliance consumes $120\,kWh$120kWh of electrical energy. If electricity costs ₹6 per kWh, calculate the total cost.

---

10. Case-Based Questions

Case Study 1 — Household Circuit

A family uses several electrical appliances at home. Each appliance needs to work independently, and the failure of one appliance should not normally stop the operation of the others.

Questions:

1. Should the appliances be connected in series or parallel?
2. What quantity remains the same across the branches?
3. Why is this arrangement more suitable for domestic circuits?
4. What happens to total resistance when another branch is added in parallel?

Answers:

1. Parallel
2. Potential difference
3. Appliances can operate independently.
4. Equivalent resistance decreases.

---

Case Study 2 — Wire Resistance

A student investigates wires of different lengths and thicknesses. The student notices that changing the wire’s dimensions changes the resistance.

Questions:

1. How does resistance depend on length?
2. How does resistance depend on cross-sectional area?
3. Write the formula connecting $R,\rho,l,A$R,ρ,l,A.
4. What happens to resistance when the wire becomes thicker?

Answers:

1. $R\propto l$R∝l
2. $R\propto1/A$R∝1/A
3. $\displaystyle R=\rho\frac lA$R=ρAl​
4. Resistance decreases.

---

Case Study 3 — Electric Heater

An electric heater converts electrical energy mainly into heat.

Questions:

1. Which effect of current is being used?
2. State the formula for heat produced.
3. What happens to heat production if current increases while $R$R and $t$t remain constant?
4. Name two other appliances that use the heating effect.

Answers:

1. Heating effect
2. $H=I^2Rt$H=I2Rt
3. Heat increases according to the square of current.
4. Electric iron and toaster.

---

11. Formula-Based MCQs

1. If $Q=60\,C$Q=60C and $t=10\,s$t=10s, $I$I equals:
A. $0.6A$0.6A
B. $6A$6A
C. $60A$60A
D. $600A$600A
Answer: B

2. If $V=20V$V=20V and $I=5A$I=5A, $R$R is:
A. $2\Omega$2Ω
B. $4\Omega$4Ω
C. $10\Omega$10Ω
D. $25\Omega$25Ω
Answer: B

3. If $I=2A$I=2A, $R=5\Omega$R=5Ω, and $t=10s$t=10s, heat produced is:
A. $20J$20J
B. $50J$50J
C. $100J$100J
D. $200J$200J
Answer: D

4. A $100V$100V appliance draws $2A$2A. Its power is:
A. $50W$50W
B. $100W$100W
C. $200W$200W
D. $500W$500W
Answer: C

5. A $2kW$2kW appliance operates for $3h$3h. Energy consumed is:
A. $1.5kWh$1.5kWh
B. $5kWh$5kWh
C. $6kWh$6kWh
D. $9kWh$9kWh
Answer: C

---

12. Identify the Correct Formula

1. Current → I=Q/tI=Q/tI=Q/t
2. Potential difference → V=W/QV=W/QV=W/Q
3. Ohm’s law → V=IRV=IRV=IR
4. Resistance → R=V/IR=V/IR=V/I
5. Resistivity relation → R=ρl/AR=\rho l/AR=ρl/A
6. Series resistance → Rs=R1+R2+⋯R_s=R_1+R_2+\cdotsRs​=R1​+R2​+⋯
7. Parallel resistance → 1Rp=1R1+1R2+⋯\frac1{R_p}=\frac1{R_1}+\frac1{R_2}+\cdotsRp​1​=R1​1​+R2​1​+⋯
8. Heat → H=I2RtH=I^2RtH=I2Rt
9. Power → P=VIP=VIP=VI
10. Electrical energy → E=PtE=PtE=Pt
11. Commercial energy conversion → 1kWh=3.6×106J1kWh=3.6\times10^6J1kWh=3.6×106J

---

13. One-Word / One-Term Questions

1. Rate of flow of electric charge — Current
2. SI unit of current — Ampere
3. SI unit of potential difference — Volt
4. SI unit of resistance — Ohm
5. SI unit of resistivity — Ohm metre
6. SI unit of power — Watt
7. Instrument measuring current — Ammeter
8. Instrument measuring potential difference — Voltmeter
9. Device used to vary resistance — Rheostat
10. Protective device against excessive current — Fuse
11. Common material used for bulb filament — Tungsten
12. Commercial unit of electrical energy — Kilowatt-hour
13. Law describing heating due to current — Joule’s law
14. Law relating $V,I,R$V,I,R at constant temperature — Ohm’s law

---

14. HOTS / Conceptual Questions

1. A wire is replaced by another wire of the same material but twice the length. Predict the change in resistance.

2. Two wires have equal length and material, but one has a larger cross-sectional area. Which has greater resistance and why?

3. Why does adding another resistor in series increase total resistance?

4. Why does adding another branch in parallel decrease equivalent resistance?

5. Why can’t ordinary domestic appliances conveniently be connected in series?

6. A resistor has constant resistance. If voltage is reduced to half, what happens to current?

7. If current through a resistor doubles while resistance and time remain constant, by what factor does heat change?

8. Why does a fuse melt when excessive current flows?

9. Why are alloys preferred over many pure metals in heating elements?

10. Two appliances have different resistances but are connected to the same voltage in parallel. Will they necessarily draw the same current? Explain using Ohm’s law.

---

⭐ Highest-Priority Questions for Exam Preparation

If you don’t have time to solve everything, focus especially on:

1. State and apply Ohm’s law.
2. Derive R=ρl/AR=\rho l/AR=ρl/A.
3. Series vs parallel resistor combinations.
4. Derive equivalent resistance in series.
5. Derive equivalent resistance in parallel.
6. Explain Joule’s law of heating.
7. Derive the three forms of electric power.
8. Explain why domestic circuits use parallel connections.
9. Explain the working and purpose of a fuse.
10. Numericals involving V=IRV=IRV=IR, R=ρl/AR=\rho l/AR=ρl/A, H=I2RtH=I^2RtH=I2Rt, P=VIP=VIP=VI, and kWh.