Electric Cells | Jamb(UTME) Physics

Simple Voltaic Cell and Its Defects

1. A simple voltaic cell is a device that generates electricity from chemical reactions.
2. It consists of two different metal electrodes (e.g., zinc and copper) immersed in an electrolyte (e.g., dilute sulfuric acid).
3. The zinc electrode acts as the anode (negative terminal) and loses electrons.
4. The copper electrode acts as the cathode (positive terminal) and gains electrons.
5. Electrons flow through an external circuit, generating an electric current.
6. A chemical reaction occurs at each electrode, producing ions in the electrolyte.
7. The main defect of a simple voltaic cell is polarization, where hydrogen bubbles form on the cathode, reducing efficiency.
8. Another defect is local action, where impurities in the zinc cause unwanted side reactions and waste energy.
9. Polarization can be reduced by using a depolarizer, like manganese dioxide.
10. Local action can be minimized by using pure zinc or amalgamated zinc (zinc coated with mercury).
    paragraph

Daniell Cell

11. The Daniell cell is an improved version of the voltaic cell that minimizes polarization.
12. It consists of a zinc anode in zinc sulfate solution and a copper cathode in copper sulfate solution.
13. A porous partition or salt bridge separates the two solutions to prevent mixing while allowing ion flow.
14. The Daniell cell produces a steady voltage of about 1.1 volts.
15. It is commonly used in laboratories as a reference cell.
16. The Daniell cell is more efficient than the simple voltaic cell because it avoids hydrogen gas formation.
    paragraph

Leclanché Cell (Wet and Dry)

17. The Leclanché cell is a primary cell that uses zinc as the anode and manganese dioxide as the cathode.
18. The electrolyte in the wet version is ammonium chloride solution.
19. The dry Leclanché cell (modern dry cell) uses a paste of ammonium chloride as the electrolyte.
20. The dry cell is compact, portable, and widely used in flashlights and toys.
21. Both types generate about 1.5 volts of electricity.
22. A key limitation is that Leclanché cells have a short lifespan and cannot be recharged.
    paragraph

Lead-Acid Accumulator

23. The lead-acid accumulator is a rechargeable battery commonly used in vehicles.
24. It consists of lead (Pb) plates as the anode and lead dioxide (PbO₂) plates as the cathode.
25. The electrolyte is dilute sulfuric acid.
26. The chemical reaction during discharge produces lead sulfate on both electrodes and water in the electrolyte.
27. During charging, the reaction is reversed, restoring the original materials.
28. It provides a voltage of about 2 volts per cell.
29. Lead-acid batteries are reliable, inexpensive, and capable of delivering high currents.
30. They are heavy, require maintenance, and have a limited lifespan.
    paragraph

Nickel-Iron (NiFe) Cell

31. The nickel-iron cell, also known as the Edison battery, is a rechargeable battery.
32. It uses nickel oxide hydroxide as the cathode and iron as the anode.
33. The electrolyte is a solution of potassium hydroxide.
34. NiFe batteries are highly durable, long-lasting, and resistant to overcharging.
35. They have a lower energy density compared to other batteries.
36. NiFe cells are used in off-grid power systems and backup power applications.
    paragraph

Lithium-Ion Battery

37. Lithium-ion batteries are rechargeable and widely used in electronics and electric vehicles.
38. They use a lithium compound as the cathode and carbon (graphite) as the anode.
39. The electrolyte is a lithium salt solution in an organic solvent.
40. Lithium-ion batteries are lightweight, have high energy density, and long cycle life.
41. They are sensitive to overcharging and require protection circuits.
42. These batteries are revolutionizing renewable energy storage and portable devices.
    paragraph

Mercury-Cadmium Battery

43. Mercury-cadmium batteries are small, button-like cells used in watches and hearing aids.
44. The anode is cadmium, the cathode is mercury oxide, and the electrolyte is a potassium hydroxide solution.
45. These batteries have a stable output voltage and long shelf life.
46. They are not environmentally friendly due to toxic mercury content and are being replaced by alternatives.
    paragraph

Maintenance of Cells and Batteries

47. Regular maintenance includes cleaning terminals to prevent corrosion.
48. Electrolyte levels should be checked and topped up with distilled water if necessary (in wet batteries).
49. Avoid overcharging batteries to prevent overheating and damage.
50. Store batteries in a cool, dry place to extend their lifespan.
51. Periodic reconditioning of rechargeable batteries can improve performance.
52. Dispose of old batteries responsibly to prevent environmental harm.
    paragraph

Arrangement of Cells

53. Cells can be connected in series to increase voltage.
54. In a series arrangement, the total voltage is the sum of the individual cell voltages.
55. Cells can be connected in parallel to increase current capacity.
56. In a parallel arrangement, the total current is the sum of the individual cell currents.
57. Proper arrangement ensures the battery meets the required voltage and current for a device.
    paragraph

Efficiency of a Cell

58. The efficiency of a cell is the ratio of its useful energy output to the energy input.
59. Efficiency is affected by internal resistance, polarization, and temperature.
60. Modern battery technologies aim to maximize efficiency by reducing energy losses and increasing storage capacity.

I recommend you check my article on the following: