An electrical safety inspector is examining a communal shower facility at a sports center. The shower room has a very hot and humid atmosphere with significant steam.
The inspector recommends that standard household rocker switches on the walls inside the shower room are replaced.
Explain why using a standard household switch in this wet and humid environment poses a major safety hazard.
Suggest a safe method or alternative design for switching the lights in the shower room on and off.
Fine sugar is transported pneumatically (blown by air) through an insulating plastic tube into a metal storage bin inside a food processing factory.
Suggest how the flow of sugar particles through the tube can lead to a large build-up of electrostatic charge on the metal bin.
On a highly humid day, a thin film of moisture forms on the surfaces of the equipment. Explain why there is no large build-up of static charge in this case.
452 exam-style questions on CIE IGCSE Physics 4.2 Electrical quantities, covering 4.2.1a Positive and negative charge, 4.2.1b Charging by friction and detecting charge, 4.2.1c Electrical conductors and insulators, 4.2.1d Electric fields and electric field patterns, 4.2.2a Electric current, charge and measuring current, 4.2.2b Conduction in metals and the direction of current, 4.2.2c Direct current and alternating current, 4.2.3a Electromotive force, 4.2.3b Potential difference and voltmeters, 4.2.4a Resistance, 4.2.4b Resistance of a metallic wire, 4.2.4c Current–voltage graphs, and 4.2.5 Electrical energy and electrical power. Each one has a worked solution and a mark scheme showing where the marks go.