A smart home security camera is powered via an electrical adapter connected to the mains supply.
The power input to the camera circuit is 8.0 W8.0\text{ W}8.0 W. The potential difference across the camera circuit is 16 V16\text{ V}16 V.
Calculate the current in the camera circuit.
The energy used by the camera each hour is 0.012 kWh0.012\text{ kWh}0.012 kWh. One unit (1 kWh1\text{ kWh}1 kWh) of electrical energy costs 25 cents.
Calculate the cost of using the camera continuously for 24 hours.
The adapter contains a step-down transformer. The number of turns NpN_pNp on the primary coil of the transformer is 4500. The primary voltage VpV_pVp applied to the transformer is 240 V240\text{ V}240 V and the secondary voltage VsV_sVs is 16 V16\text{ V}16 V.
Calculate the number of turns NsN_sNs on the secondary coil of the transformer.
The plug for the adapter circuit includes a fuse to protect the circuit and device. Explain how a fuse works to protect the circuit.
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.