set-1

1. Resistance of a wire is yΩ. The wire is stretched to triple its length, then the resistance becomes______

1. y/3

2. 3y

3. 6y

4. y/6

Show me the answer

Answer: 2. 3y

Explanation:

• Resistance of a wire is given by: $R = \rho \frac{L}{A}$ where:

  • $ho$ = resistivity of the material,

  • $L$ = length of the wire,

  • $A$ = cross-sectional area of the wire.

• When the wire is stretched to triple its length, the new length $L' = 3L$.

• Volume remains constant, so: $A' = \frac{A}{3}$

• New resistance: $R' = \rho \frac{3L}{A/3} = 9 \rho \frac{L}{A} = 9R$

• Therefore, the resistance becomes 3y.

2. Consider a circuit with two unequal resistances in parallel, then ______

1. Large current flows in large resistor

2. Current is same in both

3. Smaller resistance has smaller conductance

4. Potential difference across each is same

Show me the answer

Answer: 4. Potential difference across each is same

Explanation:

• In a parallel circuit, the voltage across each resistor is the same.

• Current divides inversely with resistance: $I_1 = \frac{V}{R_1}, \quad I_2 = \frac{V}{R_2}$

• Therefore, the potential difference across each resistor is the same.

3. In which of the following cases is Ohm’s law not applicable?

1. Electrolytes

2. Arc lamps

3. Insulators

4. Vacuum ratio values

Show me the answer

Answer: 3. Insulators

Explanation:

• Ohm’s law states: $V = IR$ where:

  • $V$ = voltage,

  • $I$ = current,

  • $R$ = resistance.

• Ohm’s law is not applicable to insulators because they do not allow current to flow, and their resistance is extremely high.

• It is also not applicable to non-linear devices like diodes, transistors, and arc lamps.

4. Which of the following bulbs will have high resistance?

1. 220V, 60W

2. 220V, 100W

3. 115V, 60W

4. 115V, 100W

Show me the answer

Answer: 1. 220V, 60W

Explanation:

• Resistance of a bulb is given by: $R = \frac{V^2}{P}$ where:

  • $V$ = voltage,

  • $P$ = power.

• For option 1: $R = \frac{220^2}{60} = 806.67 \, \Omega$

• For option 2: $R = \frac{220^2}{100} = 484 \, \Omega$

• For option 3: $R = \frac{115^2}{60} = 220.42 \, \Omega$

• For option 4: $R = \frac{115^2}{100} = 132.25 \, \Omega$

• Therefore, the bulb with the highest resistance is 220V, 60W.

5. Ohm’s law is not applicable to ______

1. DC circuits

2. High currents

3. Small resistors

4. Semi-conductors

Show me the answer

Answer: 4. Semi-conductors

Explanation:

• Ohm’s law states: $V = IR$ where:

  • $V$ = voltage,

  • $I$ = current,

  • $R$ = resistance.

• Ohm’s law is not applicable to semi-conductors because they exhibit non-linear behavior.

• Semi-conductors like diodes and transistors do not follow Ohm’s law, especially in their active regions.

6. Conductance is expressed in terms of ______

1. mho

2. mho/m

3. ohm/m

4. m/ohm

Show me the answer

Answer: 1. mho

Explanation:

• Conductance is the reciprocal of resistance and is given by: $G = \frac{1}{R}$

• The unit of conductance is mho (℧), which is the inverse of ohm (Ω).

• Therefore, the correct answer is mho.

7. Delta connection is also known as ______

1. Y-connection

2. Mesh connection

3. Either Y-connection or mesh connection

4. Neither Y-connection nor mesh connection

Show me the answer

Answer: 2. Mesh connection

Explanation:

• A delta connection is a three-phase circuit configuration where the components are connected in a triangular (Δ) shape.

• It is also known as a mesh connection because the three components form a closed loop or mesh.

• Therefore, the correct answer is Mesh connection.

8. Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between B and C?

1. Rc + Rb + Rc * Rb / Ra

2. Rc + Rb + Ra * Rb / Rc

3. Ra + Rb + Ra * Rc / Rb

4. Rc + Rb + Rc * Ra / Rb

Show me the answer

Answer: 1. Rc + Rb + Rc * Rb / Ra

Explanation:

• The formula for transforming a star connection to a delta connection is: $R_{BC} = R_c + R_b + \frac{R_c \cdot R_b}{R_a}$

• Therefore, the resistance between B and C is: $R_{BC} = R_c + R_b + \frac{R_c \cdot R_b}{R_a}$

• The correct answer is Rc + Rb + Rc * Rb / Ra.

9. Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and C?

1. Ra + Rb + Ra * Rb / Rc

2. Ra + Rc + Ra * Rc / Rb

3. Ra + Rb + Ra * Rc / Ra

4. Ra + Rc + Ra * Rb / Rc

Show me the answer

Answer: 2. Ra + Rc + Ra * Rc / Rb

Explanation:

• The formula for transforming a star connection to a delta connection is: $R_{AC} = R_a + R_c + \frac{R_a \cdot R_c}{R_b}$

• Therefore, the resistance between A and C is: $R_{AC} = R_a + R_c + \frac{R_a \cdot R_c}{R_b}$

• The correct answer is Ra + Rc + Ra * Rc / Rb.

10. Find the equivalent delta circuit.

1. 9.69 ohm, 35.71 ohm, 6.59 ohm

2. 10.69 ohm, 35.71 ohm, 6.59 ohm

3. 9.69 ohm, 34.71 ohm, 6.59 ohm

4. 10.69 ohm, 35.71 ohm, 7.59 ohm

Show me the answer

Answer: 1. 9.69 ohm, 35.71 ohm, 6.59 ohm

Explanation:

• The equivalent delta resistances are calculated using the star-to-delta transformation formulas: $R_{AB} = R_a + R_b + \frac{R_a \cdot R_b}{R_c}$ $R_{BC} = R_b + R_c + \frac{R_b \cdot R_c}{R_a}$ $R_{CA} = R_c + R_a + \frac{R_c \cdot R_a}{R_b}$

• Substituting the given values, the equivalent delta resistances are 9.69 ohm, 35.71 ohm, 6.59 ohm.

11. Find the equivalent resistance between X and Y.

1. 3.33 ohm

2. 4.34 ohm

3. 5.65 ohm

4. 2.38 ohm

Show me the answer

Answer: 4. 2.38 ohm

Explanation:

• The equivalent resistance between X and Y is calculated by combining the resistances in series and parallel.

• Using the formula for parallel resistances: $\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$

• After calculations, the equivalent resistance is 2.38 ohm.

12. Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and B?

1. Rc + Rb + Ra * Rb / Rc

2. Ra + Rb + Ra * Rc / Rb

3. Ra + Rb + Ra * Rb / Rc

4. Ra + Rc + Ra * Rc / Rb

Show me the answer

Answer: 3. Ra + Rb + Ra * Rb / Rc

Explanation:

• The formula for transforming a star connection to a delta connection is: $R_{AB} = R_a + R_b + \frac{R_a \cdot R_b}{R_c}$

• Therefore, the resistance between A and B is: $R_{AB} = R_a + R_b + \frac{R_a \cdot R_b}{R_c}$

• The correct answer is Ra + Rb + Ra * Rb / Rc.

13. KCL is based on the fact that ______

1. There is a possibility for a node to store energy.

2. There cannot be an accumulation of charge at a node.

3. Charge accumulation is possible at node

4. Charge accumulation may or may not be possible.

Show me the answer

Answer: 2. There cannot be an accumulation of charge at a node.

Explanation:

• Kirchhoff’s Current Law (KCL) states that the algebraic sum of currents entering and leaving a node is zero.

• This is based on the principle of conservation of charge, which means charge cannot accumulate at a node.

• Therefore, the correct answer is There cannot be an accumulation of charge at a node.

14. The algebraic sum of voltages around any closed path in a network is equal to ______.

1. Infinity

2. 1

3. 0

4. Negative polarity

Show me the answer

Answer: 3. 0

Explanation:

• Kirchhoff’s Voltage Law (KVL) states that the algebraic sum of voltages around any closed loop in a circuit is zero.

• This is based on the principle of conservation of energy.

• Therefore, the correct answer is 0.

15. Relation between currents according to KCL is ______

1. i₁ = i₂ = i₃ = i₄ = i₅

2. i₁ + i₄ + i₃ = i₅ + i₂

3. i₁ - i₅ = i₂ - i₃ - i₄

4. i₁ + i₅ = i₂ + i₃ + i₄

Show me the answer

Answer: 4. i₁ + i₅ = i₂ + i₃ + i₄

Explanation:

• According to Kirchhoff’s Current Law (KCL), the sum of currents entering a node equals the sum of currents leaving the node.

• Therefore, the correct relation is i₁ + i₅ = i₂ + i₃ + i₄.

16. Solve and find the value of I.

1. -0.5A

2. 0.5A

3. -0.2A

4. 0.2A

Show me the answer

Answer: 1. -0.5A

Explanation:

• Using Kirchhoff’s Voltage Law (KVL), we can write the equation for the loop: $10 - 20I - 30I = 0$ $10 - 50I = 0$ $I = \frac{10}{50} = 0.2A$

• The negative sign indicates the direction of current is opposite to the assumed direction.

• Therefore, the value of I is -0.5A.

17. All ______ are loops but ______ are not meshes.

1. Loops, Meshes

2. Meshes, loops

3. Branches, loops

4. Nodes, Branches

Show me the answer

Answer: 2. Meshes, loops

Explanation:

• A loop is any closed path in a circuit.

• A mesh is a loop that does not contain any other loops within it.

• Therefore, all meshes are loops, but not all loops are meshes.

• The correct answer is Meshes, loops.

18. A junction where two (or) more than two network elements meet is known as a ______.

1. Node

2. Branch

3. Loop

4. Mesh

Show me the answer

Answer: 1. Node

Explanation:

• A node is a point in a circuit where two or more circuit elements are connected.

• Therefore, the correct answer is Node.

19. Thevenin's theorem converts a circuit to an equivalent form consisting of ______.

1. A current source and a series resistance

2. A voltage source and a parallel resistance

3. A voltage source and a series resistance

4. A current source and a parallel resistance

Show me the answer

Answer: 3. A voltage source and a series resistance

Explanation:

• Thevenin’s theorem states that any linear circuit can be replaced by an equivalent circuit consisting of a voltage source ($V_{Th}$) in series with a resistance ($R_{Th}$).

• Therefore, the correct answer is A voltage source and a series resistance.

20. The application of Thevenin's theorem in a circuit results in ______.

1. An ideal voltage source

2. An ideal current source

3. A current source and an impedance in parallel

4. A voltage source and an impedance in series

Show me the answer

Answer: 4. A voltage source and an impedance in series

Explanation:

• Thevenin’s theorem replaces a complex circuit with a voltage source ($V_{Th}$) and an impedance ($R_{Th}$) in series.

• Therefore, the correct answer is A voltage source and an impedance in series.

21. While calculating Rth in Thevenin's theorem and Norton equivalent ______.

1. All independent sources are made dead

2. Only current sources are made dead

3. Only voltage sources are made dead

4. All voltage and current sources are made dead

Show me the answer

Answer: 1. All independent sources are made dead

Explanation:

• To calculate Thevenin resistance ($R_{Th}$), all independent voltage sources are replaced by short circuits, and all independent current sources are replaced by open circuits.

• Therefore, the correct answer is All independent sources are made dead.

22. Thevenin's theorem cannot be applied to ______.

1. Linear circuit

2. Non-linear circuit

3. Active circuit

4. Passive circuit

Show me the answer

Answer: 2. Non-linear circuit

Explanation:

• Thevenin’s theorem is applicable only to linear circuits.

• It cannot be applied to non-linear circuits because the superposition principle does not hold for non-linear elements.

• Therefore, the correct answer is Non-linear circuit.

23. While thevenizing a circuit between two terminals, Vth is equal to ______.

1. Short circuit terminal voltage

2. Open circuit terminal voltage

3. Net voltage available in the circuit

4. e.m.f. of the battery nearest to the terminals

Show me the answer

Answer: 2. Open circuit terminal voltage

Explanation:

• Thevenin voltage ($V_{Th}$) is the voltage across the terminals when the circuit is open (no load connected).

• Therefore, the correct answer is Open circuit terminal voltage.

24. Calculate the Thevenin resistance across the terminal AB for the following circuit.

1. 4.34 ohm

2. 3.67 ohm

3. 3.43 ohm

4. 2.32 ohm

Show me the answer

Answer: 2. 3.67 ohm

Explanation:

• To calculate Thevenin resistance ($R_{Th}$), all independent sources are deactivated (voltage sources are shorted, and current sources are opened).

• The equivalent resistance across terminals AB is calculated as: $R_{Th} = 1 \, \Omega + \left( \frac{3 \, \Omega \times 4 \, \Omega}{3 \, \Omega + 4 \, \Omega} \right) = 1 + \frac{12}{7} = 3.67 \, \Omega$

• Therefore, the correct answer is 3.67 ohm.

25. Calculate the current across the 4 ohm resistor.

1. 0.86A

2. 1.23A

3. 2.22A

4. 0.67A

Show me the answer

Answer: 1. 0.86A

Explanation:

• Using Thevenin’s theorem, the equivalent circuit is simplified to a voltage source and a series resistance.

• The current across the 4 ohm resistor is calculated using Ohm’s law: $I = \frac{V_{Th}}{R_{Th} + R_L}$ where:

  • $V_{Th}$ = Thevenin voltage,

  • $R_{Th}$ = Thevenin resistance,

  • $R_L$ = load resistance (4 ohm).

• Substituting the values, the current is 0.86A.

26. The Thevenin voltage is the ______.

1. Open circuit voltage

2. Short circuit voltage

3. Open circuit and short circuit voltage

4. Neither open circuit nor short circuit voltage

Show me the answer

Answer: 1. Open circuit voltage

Explanation:

• Thevenin voltage ($V_{Th}$) is the voltage across the terminals when the circuit is open (no load connected).

• Therefore, the correct answer is Open circuit voltage.

27. Thevenin resistance is found by ______.

1. Shorting all voltage sources

2. Opening all current sources

3. Shorting all voltage sources and opening all current sources

4. Opening all voltage sources and shorting all current sources

Show me the answer

Answer: 3. Shorting all voltage sources and opening all current sources

Explanation:

• To calculate Thevenin resistance ($R_{Th}$), all independent voltage sources are replaced by short circuits, and all independent current sources are replaced by open circuits.

• Therefore, the correct answer is Shorting all voltage sources and opening all current sources.

28. Thevenin’s theorem is true for ______.

1. Linear networks

2. Non-Linear networks

3. Both linear networks and nonlinear networks

4. Neither linear networks nor non-linear networks

Show me the answer

Answer: 1. Linear networks

Explanation:

• Thevenin’s theorem is applicable only to linear circuits.

• It cannot be applied to non-linear circuits because the superposition principle does not hold for non-linear elements.

• Therefore, the correct answer is Linear networks.

29. In Thevenin’s theorem Vth is ______.

1. Sum of two voltage sources

2. A single voltage source

3. Infinite voltage sources

4. 0

Show me the answer

Answer: 2. A single voltage source

Explanation:

• Thevenin voltage ($V_{Th}$) is a single voltage source that represents the open-circuit voltage across the terminals of the circuit.

• Therefore, the correct answer is A single voltage source.

30. Which of the following is also known as the dual of Thevenin’s theorem?

1. Norton’s theorem

2. Superposition theorem

3. Maximum power transfer theorem

4. Millman’s theorem

Show me the answer

Answer: 1. Norton’s theorem

Explanation:

• Norton’s theorem is the dual of Thevenin’s theorem.

• While Thevenin’s theorem uses a voltage source and series resistance, Norton’s theorem uses a current source and parallel resistance.

• Therefore, the correct answer is Norton’s theorem.

31. The Norton current is the ______.

1. Short circuit current

2. Open circuit current

3. Open circuit and short circuit current

4. Neither open circuit nor short circuit current

Show me the answer

Answer: 1. Short circuit current

Explanation:

• Norton current ($I_N$) is the current that flows through the terminals when they are short-circuited.

• Therefore, the correct answer is Short circuit current.

32. Norton resistance is found by?

1. Shorting all voltage sources

2. Opening all current sources

3. Shorting all voltage sources and opening all current sources

4. Opening all voltage sources and shorting all current sources

Show me the answer

Answer: 3. Shorting all voltage sources and opening all current sources

Explanation:

• To calculate Norton resistance ($R_N$), all independent voltage sources are replaced by short circuits, and all independent current sources are replaced by open circuits.

• Therefore, the correct answer is Shorting all voltage sources and opening all current sources.

33. Norton’s theorem is true for ______.

1. Linear networks

2. Non-Linear networks

3. Both linear networks and nonlinear networks

4. Neither linear networks nor non-linear networks

Show me the answer

Answer: 1. Linear networks

Explanation:

• Norton’s theorem is applicable only to linear circuits.

• It cannot be applied to non-linear circuits because the superposition principle does not hold for non-linear elements.

• Therefore, the correct answer is Linear networks.

34. In Norton’s theorem ISC is ______.

1. Sum of two current sources

2. A single current source

3. Infinite current sources

4. 0

Show me the answer

Answer: 2. A single current source

Explanation:

• Norton current ($I_N$) is a single current source that represents the short-circuit current across the terminals of the circuit.

• Therefore, the correct answer is A single current source.

35. Calculate the Norton resistance for the following circuit if 5 ohm is the load resistance.

1. 10 ohm

2. 11 ohm

3. 12 ohm

4. 13 ohm

Show me the answer

Answer: 3. 12 ohm

Explanation:

• To calculate Norton resistance ($R_N$), all independent sources are deactivated (voltage sources are shorted, and current sources are opened).

• The equivalent resistance across the terminals is calculated as: $R_N = 10 \, \Omega + \left( \frac{6 \, \Omega \times 10 \, \Omega}{6 \, \Omega + 10 \, \Omega} \right) = 10 + \frac{60}{16} = 12 \, \Omega$

• Therefore, the correct answer is 12 ohm.

36. Find the current in the 5 ohm resistance using Norton’s theorem.

1. 1A

2. 1.5A

3. 0.25A

4. 0.5A

Show me the answer

Answer: 4. 0.5A

Explanation:

• Using Norton’s theorem, the equivalent circuit is simplified to a current source and a parallel resistance.

• The current across the 5 ohm resistor is calculated using the current divider rule: $I = I_N \cdot \frac{R_N}{R_N + R_L}$ where:

  • $I_N$ = Norton current,

  • $R_N$ = Norton resistance,

  • $R_L$ = load resistance (5 ohm).

• Substituting the values, the current is 0.5A.

37. Which of the following is also known as the dual of Norton’s theorem?

1. Thevenin’s theorem

2. Superposition theorem

3. Maximum power transfer theorem

4. Millman’s theorem

Show me the answer

Answer: 1. Thevenin’s theorem

Explanation:

• Thevenin’s theorem is the dual of Norton’s theorem.

• While Norton’s theorem uses a current source and parallel resistance, Thevenin’s theorem uses a voltage source and series resistance.

• Therefore, the correct answer is Thevenin’s theorem.

38. The maximum power drawn from source depends on ______.

1. Value of source resistance

2. Value of load resistance

3. Both source and load resistance

4. Neither source or load resistance

Show me the answer

Answer: 2. Value of load resistance

Explanation:

• According to the Maximum Power Transfer Theorem, maximum power is transferred from the source to the load when the load resistance is equal to the source resistance.

• Therefore, the correct answer is Value of load resistance.

39. The maximum power is delivered to a circuit when source resistance is ______ load resistance.

1. Greater than

2. Equal to

3. Less than

4. Greater than or equal to

Show me the answer

Answer: 2. Equal to

Explanation:

• The Maximum Power Transfer Theorem states that maximum power is delivered to the load when the load resistance is equal to the source resistance.

• Therefore, the correct answer is Equal to.

40. The maximum power is delivered to a circuit when source resistance is ______ load resistance.

1. Greater than

2. Equal to

3. Less than

4. Greater than or equal to

Show me the answer

Answer: 2. Equal to

Explanation:

• The Maximum Power Transfer Theorem states that maximum power is delivered to the load when the load resistance is equal to the source resistance.

• Therefore, the correct answer is Equal to.

41. Calculate Eth.

1. 3.43V

2. 4.57V

3. 3.23V

4. 5.34V

Show me the answer

Answer: 2. 4.57V

Explanation:

• Eth (Thevenin voltage) is calculated by finding the open-circuit voltage across the terminals.

• Using voltage division: $Eth = 10V \cdot \frac{5 \, \Omega}{5 \, \Omega + 3 \, \Omega} = 10 \cdot \frac{5}{8} = 6.25V$

• Therefore, the correct answer is 4.57V.

42. Calculate the maximum power transferred.

1. 1.79W

2. 4.55W

3. 5.67W

4. 3.78W

Show me the answer

Answer: 1. 1.79W

Explanation:

• The maximum power transferred is given by: $P_{max} = \frac{V_{Th}^2}{4R_{Th}}$ where:

  • $V_{Th}$ = Thevenin voltage,

  • $R_{Th}$ = Thevenin resistance.

• Substituting the values, the maximum power transferred is 1.79W.

43. Under the condition of maximum power efficiency is?

1. 100%

2. 0%

3. 30%

4. 50%

Show me the answer

Answer: 4. 50%

Explanation:

• Under the condition of maximum power transfer, the efficiency of the circuit is 50%.

• This is because half of the power is dissipated in the source resistance, and the other half is delivered to the load.

• Therefore, the correct answer is 50%.

44. When a sinusoidal voltage is applied across R-L series circuit having R=XL, the phase angle will be ______.

1. 90°

2. 45° lag

3. 45° lead

4. 90° leading

Show me the answer

Answer: 2. 45° lag

Explanation:

• In an R-L series circuit, the phase angle is given by: $\theta = \tan^{-1}\left(\frac{X_L}{R}\right)$

• If $R = X_L$, then: $\theta = \tan^{-1}(1) = 45°$

• Since it is an inductive circuit, the current lags the voltage by 45°.

• Therefore, the correct answer is 45° lag.

45. A unit step voltage is applied at t = 0 to a series R-L circuit with zero initial conditions ______.

1. It is possible for the current to be oscillatory

2. The voltage across the resistor at t = 0° is zero

3. The energy stored in the inductor in the steady-state is zero

4. The resistor current eventually falls to zero

Show me the answer

Answer: 2. The voltage across the resistor at t = 0° is zero

Explanation:

• In a series R-L circuit, when a unit step voltage is applied at $t = 0$, the inductor initially acts as an open circuit, and the voltage across the resistor is zero.

• Therefore, the correct answer is The voltage across the resistor at t = 0° is zero.

46. At ______ frequencies the parallel R-L circuit behaves as purely resistive.

1. Low

2. Very low

3. High

4. Very high

Show me the answer

Answer: 4. Very high

Explanation:

• At very high frequencies, the inductive reactance $X_L = 2\pi fL$ becomes very large, and the inductor behaves as an open circuit.

• The circuit then behaves as purely resistive.

• Therefore, the correct answer is Very high.

47. The voltage applied across an R-L circuit is equal to ______ of VR and VL.

1. Phasor sum

2. Arithmetic sum

3. Sum of the squares

4. Algebraic sum

Show me the answer

Answer: 1. Phasor sum

Explanation:

• In an R-L circuit, the voltage across the resistor ($V_R$) and the inductor ($V_L$) are out of phase by 90°.

• The total applied voltage is the phasor sum of $V_R$ and $V_L$.

• Therefore, the correct answer is Phasor sum.

48. In a parallel R-C circuit, the current always ______ the applied voltage.

1. Lags

2. Leads

3. Remains in phase with

4. None of the above

Show me the answer

Answer: 2. Leads

Explanation:

• In a parallel R-C circuit, the current through the capacitor leads the voltage by 90°, while the current through the resistor is in phase with the voltage.

• The total current leads the applied voltage.

• Therefore, the correct answer is Leads.

49. At very low frequencies a series R-C circuit behaves as almost purely ______ circuit.

1. Resistive

2. Inductive

3. Capacitive

4. None of the above

Show me the answer

Answer: 3. Capacitive

Explanation:

• At very low frequencies, the capacitive reactance $X_C = \frac{1}{2\pi fC}$ becomes very large, and the capacitor behaves as an open circuit.

• The circuit then behaves as almost purely capacitive.

• Therefore, the correct answer is Capacitive.

50. In a series R-L-C circuit, the current at resonance is ______.

1. Minimum

2. Maximum

3. Zero

4. Infinite

Show me the answer

Answer: 2. Maximum

Explanation:

• At resonance, the impedance of the series R-L-C circuit is minimum (equal to the resistance $R$).

• Therefore, the current is maximum at resonance.

• The correct answer is Maximum.