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The photograph shows a step-down transformer - Edexcel - GCSE Physics - Question 2 - 2014 - Paper 1
Question 2
The photograph shows a step-down transformer. (a) Explain why step-down transformers are used in the transmission of electricity in the National Grid. (b) Transfor... show full transcript
Worked Solution & Example Answer:The photograph shows a step-down transformer - Edexcel - GCSE Physics - Question 2 - 2014 - Paper 1
Step 1
Explain why step-down transformers are used in the transmission of electricity in the National Grid.
Answer
Step-down transformers are utilized to reduce high voltages from the National Grid, such as 200,000 V, to lower voltages that can be used safely in homes and appliances, like 230 V. This is essential for several reasons:
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Efficiency and Energy Saving: High voltages minimize energy loss during transmission. Lower current is generated at reduced voltage levels, ensuring efficiency during the distribution of electricity.
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Safety: Lower voltages are safer for residential areas, reducing the risk of electrocution. High voltage transmission can be dangerous if not properly managed, hence step-down transformers play a crucial role in making electricity accessible and safe.
Step 2
Sketch a graph of an alternating current with a frequency of 2 Hz.
Answer
To sketch the graph of an alternating current with a frequency of 2 Hz, one must represent the current oscillating between positive and negative values.
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Graph Characteristics: The graph should have:
- The x-axis representing time in seconds.
- The y-axis representing current in Amperes (A).
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Cycles: As the frequency is 2 Hz, the graph will show two complete cycles within a time frame of 1 second. Each cycle will take 0.5 seconds to complete.
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Shape: The wave will cross the x-axis at regular intervals, demonstrating the alternating nature:
- The first cycle will rise to a peak positive current, drop back to zero, then decline to a peak negative current, and return to zero.
- Repeat this for the second cycle.