4. Transmission of Electrical Energy

Concept Explanation:
The transmission of electrical energy over long distances is typically done using high-voltage AC. This reduces the current for a given power level, thereby minimizing energy loss due to the resistance of the transmission lines.

Key Concepts:
- High Voltage Transmission: To reduce power loss (P = I²R), electricity is transmitted at high voltages and low currents.
- Step-Up and Step-Down Transformers: Step-up transformers are used at power stations to increase the voltage for transmission, while step-down transformers are used near consumption points to reduce the voltage to safer, usable levels.

Power Loss in Transmission:
The power loss in a transmission line is given by:
P_{loss} = I²R
where I is the current and R is the resistance of the transmission line.

Example Problem:
Calculate the power loss in a transmission line with a resistance of 0.5 Ω, carrying a current of 1000 A.

Solution:
Using the formula for power loss:
P_{loss} = I²R = (1000)² × 0.5 = 500,000 W = 500 kW
This illustrates the importance of using high voltage to reduce current and thus minimize power loss during transmission.