Internal resistance of cells and Kirchhoff’s laws - Question Bank

1. If a cell has an EMF of 1.5 V and internal resistance of 0.5 ohms, what is the current when it is short-circuited?
A) 0.5 A
B) 1.0 A
C) 3.0 A
D) Infinite
2. What is the maximum possible current that can be drawn from a cell with EMF E and internal resistance r?
A) E / R (where R is external resistance)
B) E / r
C) Zero
D) Infinite
3. Which law is particularly useful for analyzing electrical networks with multiple interconnected components?
A) Ohm's Law
B) Joule's Law
C) Kirchhoff's Laws
D) Coulomb's Law
4. When applying Kirchhoff's Second Law, if we traverse a loop in the opposite direction of an EMF source (from positive to negative terminal), the EMF is taken as:
A) Positive
B) Negative
C) Zero
D) Either positive or negative
5. What is the effect of increasing the area of electrodes in a cell on its internal resistance?
A) Increases the internal resistance
B) Decreases the internal resistance
C) Does not change the internal resistance
D) Makes internal resistance zero
6. If a cell is connected to an external resistance equal to its internal resistance, the efficiency of power transfer is:
A) 25%
B) 50%
C) 75%
D) 100%
7. What is the potential drop across the internal resistance of a cell when it is delivering current I?
A) E
B) V (terminal voltage)
C) Ir
D) E - Ir
8. Which of the following statements about internal resistance is correct?
A) It is always constant for a given cell.
B) It increases with temperature.
C) It is independent of the current drawn.
D) It depends on the state of charge of the cell.
9. In a parallel combination of two cells with identical EMFs E and internal resistances r1, r2, what is the equivalent internal resistance?
A) r1 + r2
B) (r1 + r2) / 2
C) (r1 * r2) / (r1 + r2)
D) r1
10. If the external resistance is increased to infinity (open circuit), what is the terminal voltage of the cell?
A) Zero
B) Ir
C) E - Ir
D) E
11. What is the total resistance in a circuit where a cell of EMF E and internal resistance r is connected to an external resistance R?
A) R
B) r
C) R + r
D) R - r
12. When applying Kirchhoff's Second Law, if we traverse a loop in the direction of an EMF source (from negative to positive terminal), the EMF is taken as:
A) Positive
B) Negative
C) Zero
D) Either positive or negative
13. What is the condition for a cell to be ideal (no internal resistance)?
A) Internal resistance = infinite
B) Internal resistance = 0
C) EMF = 0
D) External resistance = 0
14. If a cell's internal resistance is very high compared to the external resistance, the terminal voltage will be:
A) Close to the EMF
B) Much less than the EMF
C) Zero
D) Infinite
15. A voltmeter is used to measure potential difference. How is it connected in a circuit?
A) In series
B) In parallel
C) In series with a low resistance
D) In parallel with a low resistance
16. What is the term for the resistance offered by the electrolyte and electrodes within a cell?
A) External resistance
B) Load resistance
C) Internal resistance
D) Equivalent resistance
17. Kirchhoff's Second Law is a direct consequence of the conservation of:
A) Charge
B) Mass
C) Energy
D) Momentum
18. If a cell has an EMF of 2V and internal resistance of 1 ohm, and it is connected to an external resistance of 3 ohms, what is the terminal voltage?
A) 1.0 V
B) 1.5 V
C) 2.0 V
D) 2.5 V
19. The potential difference across the terminals of a cell when it is being charged is:
A) Less than its EMF
B) Equal to its EMF
C) Greater than its EMF
D) Zero
20. When a cell is discharged, the current flows:
A) From positive to negative terminal internally
B) From negative to positive terminal internally
C) From negative to positive terminal externally
D) From positive to negative terminal externally
21. What is the effective EMF of two cells connected in series, with EMFs E1 and E2, and E1 > E2?
A) E1 + E2
B) E1 - E2
C) E2 - E1
D) E1
22. In Kirchhoff's Second Law, if we traverse a loop in the opposite direction of the current through a resistor, the potential change is:
A) Positive
B) Negative
C) Zero
D) Depends on the EMF
23. Which of the following factors DOES NOT affect the internal resistance of a cell?
A) Nature of the electrolyte
B) Distance between electrodes
C) Area of electrodes
D) External resistance connected
24. Consider a cell with EMF E and internal resistance r. If it is connected to an external resistance R, the potential difference across R is given by:
A) E
B) Ir
C) E - Ir
D) E + Ir
25. What is the power dissipated internally by a cell with EMF E, internal resistance r, delivering current I?
A) I * E
B) I^2 * R
C) I^2 * r
D) E / r
26. If a circuit diagram has multiple loops and junctions, which method is most suitable for analysis?
A) Ohm's Law alone
B) Kirchhoff's Laws
C) Superposition Theorem
D) Thévenin's Theorem
27. Kirchhoff's First Law is also known as the:
A) Loop Rule
B) Junction Rule
C) Mesh Rule
D) Superposition Rule
28. When a cell is charged by an external source, the current flows:
A) From positive to negative terminal of the cell
B) From negative to positive terminal of the cell
C) In the same direction as discharge
D) Opposite to the direction of discharge
29. What is the unit of internal resistance?
A) Volt
B) Ampere
C) Ohm
D) Farad
30. In a parallel combination of two cells with EMFs E1, E2 and internal resistances r1, r2, for stable operation, it is generally required that:
A) E1 > E2 and r1 < r2
B) E1 < E2 and r1 > r2
C) E1 = E2 and r1 != r2
D) E1 = E2 and r1 = r2
31. What is the terminal voltage of a cell when it is not connected to any external circuit?
A) Zero
B) Slightly less than EMF
C) Equal to its EMF
D) Slightly more than EMF
32. If a cell has an EMF of 1.5 V and an internal resistance of 0.5 ohms, what is the current when connected to an external resistance of 2.5 ohms?
A) 0.5 A
B) 0.6 A
C) 1.0 A
D) 1.5 A
33. A galvanometer is a device used to detect and measure small electric currents. How is it typically connected in a circuit to measure current?
A) In parallel
B) In series
C) In series with a large resistance
D) In parallel with a large resistance
34. When applying Kirchhoff's Second Law, if we traverse a loop in the direction of the current through a resistor, the potential change is:
A) Positive
B) Negative
C) Zero
D) Depends on the EMF
35. What is the primary function of the internal resistance of a cell?
A) To increase the output voltage
B) To limit the current flowing through the cell
C) To generate heat within the cell
D) To store electrical energy
36. A cell of EMF E and internal resistance r is connected to an external resistor R. If R is increased, what happens to the current?
A) Increases
B) Decreases
C) Remains the same
D) Becomes zero
37. In a complex electrical circuit, Kirchhoff's laws are essential for:
A) Calculating the total resistance only
B) Determining the direction of current flow
C) Analyzing and solving for currents and voltages in each part
D) Finding the power dissipated by each resistor
38. What is the condition for maximum power transfer from a source to an external load?
A) External resistance is zero
B) External resistance is infinite
C) External resistance equals internal resistance
D) External resistance is twice the internal resistance
39. According to Kirchhoff's First Law, at any junction in an electrical network, the sum of currents flowing towards the junction is equal to:
A) The total resistance at the junction
B) The total voltage at the junction
C) The sum of currents flowing away from the junction
D) Zero
40. What happens to the internal resistance of a cell when its electrolyte ages or decomposes?
A) Decreases
B) Increases
C) Remains constant
D) Becomes zero
41. If a cell is short-circuited, what is the current flowing through it?
A) Zero
B) E / R (external resistance)
C) E / r (internal resistance)
D) Infinite
42. In a series combination of two cells with EMFs E1, E2 and internal resistances r1, r2, what is the equivalent EMF?
A) E1 + E2
B) E1 - E2
C) (E1 + E2) / 2
D) sqrt(E1^2 + E2^2)
43. What is the potential difference across the terminals of a cell when it is delivering current?
A) Equal to its EMF
B) Greater than its EMF
C) Less than its EMF
D) Zero
44. When a cell is being charged, the terminal voltage is related to its EMF and internal resistance by which formula?
A) V = E + Ir
B) V = E - Ir
C) V = Ir
D) V = E
45. If a cell has an EMF of E and internal resistance r, and it is connected to an external resistance R, what is the current flowing through the circuit?
A) E / R
B) E / r
C) E / (R + r)
D) E / (R - r)
46. What does Kirchhoff's Second Law represent in terms of energy?
A) Conservation of energy
B) Conservation of charge
C) Conservation of momentum
D) Conservation of mass
47. Kirchhoff's First Law is based on the conservation of which quantity?
A) Energy
B) Momentum
C) Charge
D) Mass
48. Which law states that the algebraic sum of EMFs and potential drops in any closed circuit is zero?
A) Ohm's Law
B) Joule's Law
C) Kirchhoff's Second Law (Voltage Law)
D) Kirchhoff's First Law (Current Law)
49. What is the SI unit of electromotive force (EMF)?
A) Ampere
B) Ohm
C) Volt
D) Watt
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