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Figure 6 shows part of the UK National Grid system for the supply of electricity to homes - Edexcel - GCSE Physics Combined Science - Question 3 - 2023 - Paper 2
Question 3
Figure 6 shows part of the UK National Grid system for the supply of electricity to homes. Electricity supplied to homes has a frequency of ☐ A 0.02 Hz ☐ B 20 Hz ☐... show full transcript
Worked Solution & Example Answer:Figure 6 shows part of the UK National Grid system for the supply of electricity to homes - Edexcel - GCSE Physics Combined Science - Question 3 - 2023 - Paper 2
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Explain why the National Grid uses high voltages with small currents to transfer electricity from power stations.
Answer
The National Grid uses high voltages to reduce the current that flows through the transmission lines. This is important for two main reasons:
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Reduced Energy Losses: Higher voltages result in lower currents, which decreases the power loss due to heat in the wires. This heat loss is proportional to the square of the current ( where P is power loss, I is current, and R is resistance). Thus, by transmitting at high voltages, the National Grid minimizes energy losses during transmission.
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Efficiency of Transmission: Transmitting electricity at higher voltages allows the use of thinner wires, reducing the amount of material needed and thus the overall cost of infrastructure. This makes it more efficient to transport electricity over long distances from power stations to homes.