Physics 2010 JAMB Past Questions - Question 39: Power supply is transmitted in at a very high voltage and low current in order to

Correct Answer

B

Explanation

Power supply is transmitted at a very high voltage and low current for several important reasons, primarily related to the efficiency and safety of electrical distribution. This concept is based on the principles of electrical engineering and is commonly used in high-voltage transmission lines. Here are the key reasons for transmitting power at high voltage and low current:

1. Reduced I²R Losses: Power loss in electrical conductors is proportional to the square of the current (I²) and the resistance (R) of the wires. By transmitting power at high voltage and low current, the I²R losses are significantly reduced. Lower current means less power is lost as heat due to the resistance of the transmission lines, making the overall transmission more efficient.

2. Efficient Long-Distance Transmission: High voltage allows for the efficient transmission of electrical power over long distances. Lower current reduces the energy lost as heat during transmission, making it possible to transport electricity from power generation stations to distant locations with minimal losses.

3. Voltage Regulation: High voltage helps maintain a more stable voltage level throughout the transmission system. This is important for ensuring that the voltage received by consumers is within acceptable limits and does not fluctuate significantly.

4. Minimized Conductor Size: Transmitting power at high voltage allows for the use of smaller conductor sizes, reducing the cost of materials and infrastructure needed for the transmission lines.

5. Safety: High-voltage power transmission is generally considered safer for the public because it reduces the need for numerous substations and transformers at lower voltages. High-voltage lines can be located in less populated areas, reducing the risk of accidents and exposure to high-voltage equipment.

6. Lower Voltage Drop: High-voltage transmission reduces voltage drop along the transmission lines, which is important for delivering electricity at the required voltage levels to end-users.

7. Power Generation Efficiency: Many power generation methods, such as generators and transformers, operate more efficiently at higher voltages. Transmitting power at high voltage allows power generation facilities to work more efficiently, reducing losses in the overall energy conversion process.

However, power is typically transformed to lower voltages for distribution to homes and businesses, as high-voltage electricity is unsafe and not suitable for most appliances and equipment. Substations and transformers are used to step down the voltage to levels that are safe and usable for end-users. This step-down process occurs progressively as the electricity moves through the grid, from high-voltage transmission lines to medium-voltage distribution lines, and finally to low-voltage lines in residential and commercial areas.