Fundamentals, Units, and Effects of Electric Current
1. What is the SI unit of electric current?
A) Coulomb
B) Ampere
C) Volt
D) Ohm
Answer: B) Ampere. The Ampere (A) is the standard SI unit defined as one coulomb of charge flowing per second.
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2. Electric current is defined as the rate of flow of:
A) Energy
B) Resistance
C) Electric charge
D) Power
Answer: C) Electric charge. Current ($I$) is defined mathematically as the charge ($Q$) passing through a cross-section per unit time ($t$), i.e., $I = Q/t$.
3. Which instrument is used to measure electric current?
A) Voltmeter
B) Ammeter
C) Ohmmeter
D) Galvanometer
Answer: B) Ammeter. An ammeter is connected in series in a circuit to measure the flow of current.
4. What is the direction of 'conventional current'?
A) Direction of electron flow
B) Direction of positive charge flow
C) Always from negative to positive
D) No specific direction
Answer: B) Direction of positive charge flow. By convention, current is assumed to flow from the positive terminal to the negative terminal.
5. Which material is the best conductor of electricity?
A) Copper
B) Silver
C) Gold
D) Aluminum
Answer: B) Silver. Silver has the highest electrical conductivity of all metals at room
temperature.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
6. The heating effect of electric current is governed by which law?
A) Ohm’s Law
B) Joule’s Law
C) Faraday’s Law
D) Kirchhoff’s Law
Answer: B) Joule’s Law. Joule’s Law of heating states that $H = I^2Rt$, where $H$ is heat produced, $I$ is current, $R$ is resistance, and $t$ is time.
7. If the length of a conductor is doubled, its resistance:
A) Remains same
B) Halves
C) Doubles
D) Increases four times
Answer: C) Doubles. Resistance is directly proportional to the length of the conductor ($R \propto L$).
8. What happens to the resistance of a metallic conductor as temperature increases?
A) It decreases
B) It remains constant
C) It increases
D) It becomes zero
Answer: C) It increases. Increased temperature leads to increased atomic vibrations, which impede electron flow.
9. The unit of potential difference is:
A) Watt
B) Ampere
C) Volt
D) Coulomb
Answer: C) Volt. The Volt (V) represents the energy per unit charge (Joules per Coulomb).
10. Ohm’s Law relates:
A) Current and Charge
B) Voltage, Current, and Resistance
C) Power and Time
D) Resistance and Heat
Answer: B) Voltage, Current, and Resistance. Ohm’s Law states $V = IR$.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
11. Which device stores electrical energy in an electric field?
A) Resistor
B) Battery
C) Capacitor
D) Inductor
Answer: C) Capacitor. Capacitors store energy in an electric field between two conductive plates.
12. A short circuit is caused by:
A) Extremely high resistance
B) Extremely low resistance
C) Lack of voltage
D) Constant current
Answer: B) Extremely low resistance. A short circuit creates a path of near-zero resistance, leading to a massive, dangerous surge in current.
13. The unit of electrical resistivity is:
A) Ohm
B) Ohm-meter
C) Ohm/meter
D) Siemens
Answer: B) Ohm-meter. Derived from $R = \rho(L/A)$, so $\rho = (R \times A) / L$, units: $\Omega \cdot m$.
14. An ideal ammeter should have:
A) Infinite resistance
B) Very high resistance
C) Zero resistance
D) Variable resistance
Answer: C) Zero resistance. This prevents the ammeter from adding resistance to the circuit it is measuring.
15. An ideal voltmeter should have:
A) Infinite resistance
B) Zero resistance
C) Very low resistance
D) Moderate resistance
Answer: A) Infinite resistance. This ensures it draws no current from the circuit branch being measured.
16. Which effect is responsible for the operation of an electric fuse?
A) Magnetic effect
B) Heating effect
C) Chemical effect
D) Lighting effect
Answer: B) Heating effect. A fuse melts when current exceeds a limit due to heat generation.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
17. What is the unit of electric power?
A) Joule
B) Watt
C) Volt-Ampere
D) kilowatt-hour
Answer: B) Watt. Power is the rate of doing work or consuming energy ($1 W = 1 J/s$).
18. In a series circuit, what remains the same across all components?
A) Voltage
B) Power
C) Current
D) Resistance
Answer: C) Current. In series, the current has only one path to follow.
19. In a parallel circuit, what remains the same across all branches?
A) Current
B) Power
C) Voltage
D) Resistance
Answer: C) Voltage. All components in parallel are connected to the same potential difference nodes.
20. Which material is used for the filament of an incandescent bulb?
A) Copper
B) Iron
C) Tungsten
D) Aluminum
Answer: C) Tungsten. It has a very high melting point, allowing it to withstand extreme heat to produce light.
21. Electrical energy consumed is measured in:
A) Watts
B) Kilowatt-hours (kWh)
C) Joules per second
D) Amperes
Answer: B) Kilowatt-hours (kWh). This is the standard unit for utility billing.
22. How many electrons equal 1 Coulomb of charge?
A) $1.6 \times 10^{-19}$
B) $6.25 \times 10^{18}$
C) $9.1 \times 10^{-31}$
D) $1.0 \times 10^{6}$
Answer: B) $6.25 \times 10^{18}$. Derived from $1 / (1.602 \times 10^{-19})$.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
23. Which of these is a semiconductor?
A) Iron
B) Silicon
C) Plastic
D) Gold
Answer: B) Silicon. Semiconductors have conductivity between conductors and insulators.
24. The chemical effect of electric current is the principle behind:
A) Electric motors
B) Toasters
C) Electroplating
D) Transformers
Answer: C) Electroplating. It involves the deposition of metal ions onto a surface via electrolysis.
25. A rheostat is used to:
A) Measure current
B) Increase voltage
C) Vary resistance
D) Store charge
Answer: C) Vary resistance. It allows for the adjustment of current in a circuit.
26. Which law states that the sum of currents entering a junction equals the sum leaving?
A) Ohm’s Law
B) Kirchhoff’s Current Law
C) Joule’s Law
D) Faraday’s Law
Answer: B) Kirchhoff’s Current Law. This represents the principle of conservation of charge.
27. What is the resistance of an ideal insulator?
A) Zero
B) Very low
C) Infinite
D) Constant
Answer: C) Infinite. Ideal insulators do not allow any current flow.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
28. If voltage is doubled and resistance remains constant, current:
A) Remains same
B) Halves
C) Doubles
D) Quadruples
Answer: C) Doubles. By $I = V/R$, current is directly proportional to voltage.
29. Which of the following is NOT an effect of electric current?
A) Heating
B) Magnetic
C) Chemical
D) Gravitational
Answer: D) Gravitational. Current does not create a gravitational field.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
30. The magnetic effect of current was discovered by:
A) Oersted
B) Faraday
C) Ohm
D) Joule
Answer: A) Oersted. He observed the deflection of a compass needle near a current-carrying wire.
31. The product of voltage and current gives:
A) Resistance
B) Power
C) Energy
D) Charge
Answer: B) Power. $P = V \times I$.
32. Which alloy is often used in making standard resistors?
A) Copper
B) Aluminum
C) Constantan
D) Iron
Answer: C) Constantan. It has a low temperature coefficient, meaning its resistance stays stable as it heats up.
33. Power dissipated in a resistor is given by:
A) $V^2/R$
B) $IR$
C) $V/I$
D) $Q/t$
Answer: A) $V^2/R$. Derived from $P = VI$ and $V = IR$.
34. The charge of an electron is approximately:
A) $1.6 \times 10^{-19}$ C
B) $6.25 \times 10^{18}$ C
C) $9.1 \times 10^{-31}$ C
D) $1.6 \times 10^{19}$ C
Answer: A) $1.6 \times 10^{-19}$ C. This is the fundamental unit of electric charge.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
35. If three 10 $\Omega$ resistors are in series, the total resistance is:
A) 3.33 $\Omega$
B) 10 $\Omega$
C) 30 $\Omega$
D) 100 $\Omega$
Answer: C) 30 $\Omega$. Series resistance is the sum of individual resistances: $10+10+10 = 30$.
36. If three 10 $\Omega$ resistors are in parallel, the total resistance is:
A) 3.33 $\Omega$
B) 10 $\Omega$
C) 30 $\Omega$
D) 0.33 $\Omega$
Answer: A) 3.33 $\Omega$. $1/R_p = 1/10 + 1/10 + 1/10 = 3/10$; so $R_p = 10/3 = 3.33$.
37. Which of the following defines potential difference?
A) Energy per unit time
B) Work done per unit charge
C) Charge per unit time
D) Force per unit charge
Answer: B) Work done per unit charge. $V = W/Q$.
38. What does AC stand for?
A) Actual Current
B) Alternating Current
C) Atomic Current
D) Advanced Circuit
Answer: B) Alternating Current. Current that periodically reverses direction.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
39. In a DC circuit, current flows:
A) In one direction
B) In both directions
C) Randomly
D) Only when voltage is zero
Answer: A) In one direction. Direct Current (DC) is unidirectional.
40. The property of a conductor to oppose current flow is:
A) Voltage
B) Resistance
C) Capacitance
D) Inductance
Answer: B) Resistance. Resistance measures the obstruction to the flow of charge.
41. Which unit is used for conductance?
A) Ohm
B) Siemens
C) Joule
D) Watt
Answer: B) Siemens. Conductance is the reciprocal of resistance.
42. Why is aluminum used for overhead power lines?
A) Higher conductivity than copper
B) Higher density
C) Lighter weight and lower cost
D) Does not heat up
Answer: C) Lighter weight and lower cost. While less conductive than copper, its physical properties make it ideal for long-distance transport.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
43. The work done to move 1 Coulomb of charge across 1 Volt potential is:
A) 1 Joule
B) 1 Watt
C) 1 Ampere
D) 1 Ohm
Answer: A) 1 Joule. Since $W = V \times Q$.
44. A battery converts which type of energy to electrical energy?
A) Heat
B) Chemical
C) Mechanical
D) Nuclear
Answer: B) Chemical. Chemical reactions within the cell create potential difference.
45. Which of these materials is an electrolyte?
A) Distilled water
B) Copper sulfate solution
C) Dry plastic
D) Pure rubber
Answer: B) Copper sulfate solution. It contains free ions capable of conducting electricity.
46. What happens to the total resistance in a circuit when more resistors are added in parallel?
A) Increases
B) Decreases
C) Stays same
D) Becomes infinite
Answer: B) Decreases. Adding parallel paths always reduces the total equivalent resistance.BOOK BUY LINK-#https://www.apnitest.in/shop/pspcl-alm-assistant-lineman-book-and-test-series-in-punjabi-language-2026-335?search=ALM
47. A "blown" fuse is indicated by:
A) A continuous circuit
B) An open circuit
C) Increased voltage
D) Decreased resistance
Answer: B) An open circuit. The fuse wire melts, creating a gap that stops current flow.
48. Current density is defined as:
A) Current per unit area
B) Current per unit length
C) Charge per unit area
D) Voltage per unit area
Answer: A) Current per unit area. Represented by $J = I/A$.
49. Which of the following can detect small currents?
A) Voltmeter
B) Galvanometer
C) Wattmeter
D) Ohmmeter
Answer: B) Galvanometer. It is highly sensitive to very small currents.
50. What is the relationship between power, current, and resistance?
A) $P = I^2R$
B) $P = IR$
C) $P = V/I$
D) $P = R/I^2$
Answer: A) $P = I^2R$. Derived by substituting Ohm's law ($V=IR$) into the power formula ($P=VI$).