An electric kettle with a metal outer casing is connected to the mains supply using a cable containing live, neutral, and earth wires. A hair dryer with a plastic outer casing is designed with double insulation and is connected using a cable containing only live and neutral wires.
Which of the following explains why the hair dryer does not require an earth wire?
The plastic casing of the hair dryer is an electrical insulator, preventing any risk of electric shock if a live wire touches the casing.
The hair dryer is fitted with an internal fuse, whereas the kettle is not.
The hair dryer operates at a much lower voltage than the kettle.
The kettle requires a path for direct current (DC) to flow back to the mains.
135 exam-style questions on CIE IGCSE Physics Electrical safety, covering Electrical safety. Each one has a worked solution and a mark scheme showing where the marks go.