Internal resistance, potential difference and emf of a cell, combinations of cells in series and parallel - One Line Questions

1. The internal resistance of a cell can be determined experimentally using a voltmeter and an ammeter. If the terminal voltage is V when current I is drawn, and the EMF is E when no current is drawn, what is the internal resistance? — (E - V) / I
2. If two cells with EMFs E1, E2 and internal resistances r1, r2 are connected in parallel, what is the equivalent EMF (E_eq)? — (E1*r2 + E2*r1) / (r1 + r2)
3. If two cells with EMFs E1, E2 and internal resistances r1, r2 are connected in parallel, what is the equivalent internal resistance (r_eq)? — (r1 * r2) / (r1 + r2)
4. A cell of EMF 2V and internal resistance 0.1 ohm is connected to an external resistance of 0.9 ohm. What is the current in the circuit? — 2 A
5. A cell of EMF 1.2V and internal resistance 0.5 ohm drives a current through an external resistance of 2.5 ohm. What is the power dissipated in the external resistance? — 0.48 W
6. A cell of EMF 1.5V and internal resistance 1 ohm is connected to an external resistance of 2 ohms. What is the terminal voltage? — 1.0V
7. A battery consists of 10 cells, each of EMF 1.5V and internal resistance 0.2 ohm, connected in series. If this battery is connected to an external resistance of 3 ohm, what is the current? — 0.5A
8. Consider a circuit with two cells in parallel, E1=2V, r1=1 ohm and E2=3V, r2=1 ohm. What is the equivalent EMF? — 2.5V
9. For parallel combination of cells to be most effective in providing current, their EMFs should be: — Equal
10. If 'n' identical cells, each of EMF E and internal resistance r, are connected in series, what is the total EMF? — nE
11. If 'n' identical cells, each of EMF E and internal resistance r, are connected in parallel, what is the total EMF? — E
12. If a cell of EMF E and internal resistance r is connected to an external resistance R, what is the current flowing through the circuit? — E / (R + r)
13. What is the relationship between EMF (E), terminal voltage (V), current (I), and internal resistance (r) when a cell is discharging? — E = V + Ir
14. What is the power dissipated in the external resistance R when a cell of EMF E and internal resistance r is connected to it? — E^2 * R / (R + r)^2
15. What is the power dissipated internally in the cell when a cell of EMF E and internal resistance r is connected to an external resistance R? — E^2 * r / (R + r)^2
16. If a cell's EMF is E and its internal resistance is r, what is the maximum power that can be delivered to an external resistance? — E^2 / (4r)
17. If a battery of EMF E and internal resistance r is short-circuited, what is the current? — E/r
18. If two cells with EMFs E1, E2 and internal resistances r1, r2 are connected in series, what is the total EMF? — E1 + E2
19. If two cells are connected in series in opposition, what is the resultant EMF? — E1 - E2 (assuming E1 > E2)
20. What is defined as the opposition to the flow of current within the source of electromotive force itself? — Internal Resistance
21. What is the potential difference across the terminals of a source called when current is being drawn from it? — Terminal Voltage
22. Four identical cells, each of EMF 1.5V and internal resistance 0.5 ohm, are connected in parallel. What is the equivalent EMF and internal resistance? — EMF=1.5V, r=0.125 ohm
23. A battery of 6 cells, each of EMF 2V and internal resistance 0.5 ohm, are connected in series. What is the total EMF and total internal resistance? — EMF=12V, r=3 ohm
24. Two cells, 2V/0.5 ohm and 3V/1 ohm, are connected in series aiding. What is the total EMF and total internal resistance? — EMF=5V, r=1.5 ohm
25. If two cells with EMFs E1 and E2 and internal resistances r1 and r2 are connected in parallel such that they are aiding, and E1 > E2, then the current will flow: — From cell 1 to cell 2
26. When multiple cells are connected in parallel, the equivalent internal resistance is always: — Less than the smallest individual internal resistance
27. What happens to the terminal voltage of a cell when it is discharging and the external resistance decreases? — Decreases
28. For an ideal cell, what is its internal resistance? — Zero
29. Which quantity represents the total energy supplied by a source per unit charge when no current is drawn from it? — Electromotive Force (EMF)
30. What happens to the internal resistance of a cell as its electrolyte ages or degrades? — It increases
31. In a series combination of cells, if one cell is reversed, how does it affect the total EMF? — It decreases
32. A cell of EMF E and internal resistance r is connected to an external resistance R. If R is increased, what happens to the terminal voltage? — It increases
33. If a battery of N identical cells in series is connected to an external resistance R, and one cell is accidentally reversed, how is the total EMF affected? — It decreases by 2E
34. If 'n' identical cells, each of EMF E and internal resistance r, are connected in series, what is the total internal resistance? — nr
35. If 'n' identical cells, each of EMF E and internal resistance r, are connected in parallel, what is the total internal resistance? — r/n
36. What is the condition for maximum current when a battery of EMF E and internal resistance r is connected to an external resistance R? — R = r
37. If N cells are connected in parallel, and each cell has EMF E and internal resistance r, to obtain maximum current from this combination, what should be the external resistance R? — R = r/N
38. If two cells with EMFs E1, E2 and internal resistances r1, r2 are connected in series, what is the total internal resistance? — r1 + r2
39. Which combination of cells is generally preferred for providing a large current at low voltage? — Parallel combination
40. The internal resistance of a cell is affected by which of the following factors? — All of the above
41. In a parallel combination of cells, if the cells have unequal EMFs but equal internal resistances, what is the equivalent EMF? — The average of the EMFs
42. If two cells are connected in parallel, and one cell has a much larger EMF than the other, what is the likely outcome? — The cell with lower EMF will charge the cell with higher EMF.
43. Two cells with EMFs 2V and 1V and internal resistances 1 ohm and 2 ohm respectively are connected in parallel. Which condition must be met for the formula E_eq = (E1r2 + E2r1) / (r1+r2) to be valid? — The cells must be connected aiding
44. What is the primary reason a battery's voltage drops when it's nearly depleted? — The internal resistance increases significantly.
45. When cells are connected in series, the total EMF is the algebraic sum of individual EMFs. This is true when: — They are connected in the same direction
46. When cells are connected in series, the total internal resistance is the sum of individual internal resistances. This is true when: — They are connected in the same direction
47. When a cell is being charged, the terminal voltage is related to EMF and internal resistance by which formula? — V = E + Ir
48. When a cell is discharging, the terminal voltage is related to EMF and internal resistance by which formula? — V = E - Ir
49. What is the unit of internal resistance? — Ohm (Ω)
50. When is the potential difference across the terminals of a cell equal to its EMF? — When no current is drawn from the cell (open circuit)
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