A student investigates how the thickness of a fuse wire affects the maximum current it can carry before melting (blowing).
The student sets up the circuit shown below using a low-voltage variable DC power supply, an ammeter, a variable resistor, and a holder to secure a short length of test fuse wire.
Describe a method the student could use to collect the data needed to plot a graph of threshold current (the current at which the wire melts) against the diameter of the fuse wire.
Which of the following statements correctly describes the graph of threshold current (yyy-axis) against wire diameter (xxx-axis) for a fuse wire under these conditions?
- A: A horizontal line showing that threshold current remains constant as diameter increases.
- B: A curve starting at a high current and decreasing to zero.
- C: A line or curve showing that threshold current increases as the wire diameter increases.
- D: A straight line with a constant negative gradient.
The student uses a low-voltage DC power supply for this fuse investigation. Explain why a person touching a domestic mains live wire (at 230 V) is at a severe risk of electric shock, whereas touching the earth wire of a properly functioning appliance is not.
Domestic uses and safety Questions
Practise AQA GCSE Physics Domestic uses and safety with exam-style questions for Foundation and Higher tier. 13 questions covering Direct and alternating potential difference and Mains electricity, matched to the AQA GCSE Physics (8463) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.