dexcel/questions","basePath":"/gcse/physics/edexcel/mains-electricity-and-safety/questions","formulaUrl":null,"initialIndex":4,"initialQuestionWindow":[{"id":"0a395a05-9177-4c23-861d-a5a4cd51a506","revisionId":"3284b56b-2777-498f-b226-cae1fc7d7c90","questionNumber":null,"questionType":"LA","specification":"Figure 1 shows the internal wiring of a three-pin plug used to connect a toaster with a metal casing to the mains electrical supply.\n\n![Diagram showing the inside of a standard UK three-pin plug.](https://assets.mathsgenie.co.uk/aqa-qb/1529bab2-fa57-4d5d-b6ed-c5b08f8720e8.png)\n\nA fault develops in the toaster, causing the live wire to come loose and make contact with the metal casing.","difficulty":5,"difficultyBand":"medium","totalMarks":6,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"d7c39a0c-c01b-49c1-a847-f2508fc0531e","label":null,"content":"Explain how the safety features of the plug protect a user from receiving an electric shock when this fault occurs.","markscheme":"- States that the earth wire is connected directly to the metal casing of the toaster B1\n- Explains that the earth wire has a very low electrical resistance B1\n- Explains that when the live wire touches the metal casing, it completes a circuit with the earth wire, causing a very large current to flow M1\n- Identifies that this large current passes through the fuse (which is connected in series with the live wire) M1\n- Explains that the large current heats the fuse wire above its melting point, causing it to melt ('blow') and break the circuit A1\n- Concludes that this disconnects/isolates the live supply from the appliance, removing potential from the casing and preventing electric shock A1","marks":6,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"earth_fault_fuse","label":"Trace the fault current","steps":[{"type":"text","order":0,"title":"Identify the earth path","content":"The earth wire is connected directly to the toaster’s metal casing. It has a very low electrical resistance.\n\nThis earns both B1 marks: state the direct connection to the casing and the low resistance."},{"type":"text","order":2,"title":"Complete the fault circuit","content":"When the live wire touches the metal casing, it completes a circuit through the earth wire. Because this earth path has very low resistance, a **very large current** flows: this is the fault current. **This earns the M1.**","highlights":[{"text":"live wire to come loose and make contact with the metal casing","location":"specification"}]},{"type":"text","order":3,"title":"Put the fuse first","content":"The large fault current also passes through the **fuse**, because the fuse is connected **in series** with the live wire. “In series” means it is on the only route for current in that part of the circuit.\n\nThis identifies the fuse and its position, earning the next M1. The fuse is not connected to the earth wire.","highlights":[{"text":"Figure 1 shows the internal wiring of a three-pin plug","location":"specification"}]},{"type":"text","order":4,"title":"Blow the fuse","content":"The very large current heats the fuse wire above its melting point. The wire melts — the fuse **blows** — and this breaks the circuit.\n\nFor the A1, explain both the heating and the melting; writing only “the fuse blows” does not explain why it happens."},{"type":"text","order":5,"title":"State the protection","content":"Once the fuse has broken the circuit, the live supply is disconnected from the toaster. The metal casing is no longer at a dangerous potential, so a user cannot receive an electric shock.\n\nThat clear final link from a broken circuit to a safe casing earns the last A1."}]}],"generatedAt":"2026-07-22T09:31:31.120Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"29365194-64b6-4d09-b128-db81e00143d4","revisionId":"df2d2dda-464c-4f4f-a394-016681b5129b","questionNumber":null

Mains electricity and safety

Question 1

Mains electricity and safety Questions

Mains electricity and safety

Question 1

Mains electricity and safety Questions