Electrical Energy and Power | Jamb(UTME)

Concepts of Electrical Energy and Power

1. Electrical energy is the energy transferred by an electric current in a circuit.
2. It is calculated using the formula $E = P \times t$, where $E$ is energy, $P$ is power, and $t$ is time.
3. Electrical power is the rate at which electrical energy is consumed or produced.
4. Power is measured in watts (W), where 1 watt equals 1 joule per second.
5. The formula for power is $P = V \times I$, where $V$ is voltage and $I$ is current.
6. Higher power devices consume more energy in a given time.
   paragraph

Commercial Unit of Electric Energy

7. The commercial unit of electrical energy is the kilowatt-hour (kWh).
8. One kilowatt-hour equals the energy consumed by a device using 1,000 watts for one hour.
9. Electric companies use kWh to calculate electricity bills.
10. Energy consumption in kWh is calculated as $Energy (kWh) = Power (kW) \times Time (hours)$.
    paragraph

Electric Power Transmission

11. Electric power transmission is the process of delivering electricity from power plants to homes and businesses.
12. Transmission occurs through high-voltage power lines to reduce energy losses.
13. High voltage minimizes current, which reduces heat loss in wires.
14. Step-up transformers increase voltage for transmission.
15. Step-down transformers decrease voltage for safe usage in homes and industries.
16. Efficient power transmission reduces energy waste and ensures reliability.
    paragraph

Heating Effects of Electric Current

17. When an electric current flows through a conductor, it produces heat.
18. The heating effect depends on the current, resistance, and time, as shown in $H = I^2 R t$.
19. This is the principle behind electric heaters, toasters, and irons.
20. Fuses and circuit breakers use the heating effect to disconnect circuits when excessive current flows.
21. Excess heat can damage wires and appliances, making insulation and proper wiring crucial.
    paragraph

Electrical Wiring of Houses

22. Electrical wiring connects power supply to devices in homes and buildings.
23. It uses insulated copper or aluminum wires for safety and conductivity.
24. Circuits are classified as lighting circuits or power circuits based on their load capacity.
25. A main distribution board houses circuit breakers and switches for control.
26. Earthing is essential to protect against electric shocks.
27. Color-coded wires (e.g., live, neutral, earth) ensure safe and proper connections.
    paragraph

Use of Fuses

28. A fuse is a safety device that prevents excess current from damaging circuits.
29. It consists of a thin wire that melts when current exceeds a safe limit.
30. The melting of the fuse wire breaks the circuit, stopping the flow of electricity.
31. Fuses protect appliances from short circuits and overloading.
32. They are rated by current capacity (e.g., 5A, 10A) and must be chosen based on the appliance's load.
33. Fuses should be replaced with the correct rating to ensure safety.
34. Modern homes often use circuit breakers, which are reusable and more reliable.
    paragraph

Additional Points on Electrical Energy and Power

35. Energy efficiency is key to reducing electricity bills and conserving resources.
36. Compact fluorescent lamps (CFLs) and LED lights use less power than incandescent bulbs.
37. Electric motors convert electrical energy into mechanical energy for various appliances.
38. Power factor measures how efficiently electrical power is used in AC circuits.
39. Low power factor increases energy loss and costs for businesses.
    paragraph

Additional Points on Electric Power Transmission

40. Renewable energy sources like wind and solar integrate into the power grid for sustainable electricity.
41. Smart grids use digital technology for efficient energy distribution and monitoring.
42. Losses in transmission lines are minimized by using high-quality conductors.
43. Underground cables reduce power interruptions caused by weather but are more expensive.
    paragraph

Additional Points on Heating Effects of Electric Current

44. Joule's law explains the heating effect of electric current and its practical uses.
45. Electric ovens and kettles utilize the heating effect for cooking and boiling water.
46. Electric resistance heaters use coils of high-resistance materials like nichrome.
47. Overheating in circuits can cause fires, making circuit protection essential.
    paragraph

Additional Points on Electrical Wiring of Houses

48. Proper wiring layouts prevent overloading and ensure balanced power distribution.
49. Three-pin plugs and sockets are designed for safety, with the third pin connected to the earth wire.
50. Regular inspection and maintenance of house wiring prevent accidents and ensure efficiency.

I recommend you check my article on the following: