An electric filament lamp has "230 V,46 W230\text{ V}, 46\text{ W}230 V,46 W" marked on it. Its filament is a coiled coil of fine tungsten wire.
To emit bright light, the filament has to reach a very high temperature. Suggest why design features such as coiling the filament help to achieve this high temperature.
If your hand is close to the lamp when it is switched on for a few seconds, you can feel warmth from the lamp but the glass will remain cool.
By what method has the thermal energy reached your hand?
The markings on the lamp give electrical information about the lamp when it is operating normally. State the value of:
When the lamp is working normally, its resistance is 1150 Ω1150\ \Omega1150 Ω.
Calculate the current in the lamp.
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.