Photo AI
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 essential in the transmission of electricity for several reasons:
-
Voltage Reduction: They decrease the voltage from high levels, for example, 200,000 V, to safer levels, like 230 V, which is necessary for household use.
-
Efficiency and Energy Saving: By reducing the voltage, the transformers help to minimize energy losses during transmission. High voltages can lead to more significant energy loss, which makes the system less efficient.
-
Safety: Lowering voltage enhances safety for end users. High voltages can be dangerous and increase the risk of electrocution.
-
Application to Homes and Appliances: Step-down transformers allow electricity to be used more effectively within homes and factories, ensuring appliances operate safely and efficiently.
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, follow these guidelines:
-
Time Axis: Label the x-axis as 'time / s' and mark intervals at 0.5 seconds.
-
Current Axis: Label the y-axis as 'current / A' and ensure it ranges from -2 A to +2 A.
-
Curve Sketching: Draw a sinusoidal wave that oscillates above and below the x-axis, completing two full cycles in 1 second. The peaks should reach up to 2 A and down to -2 A.
-
Key Points: Identify points such as the maximum positive current at 0.25 s and the maximum negative current at 0.75 s.