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UPPCS Physics Gap Sheet: Electronics and Energy Devices.
UPPCS has asked 19 of these. 12 have not been asked yet. Lock the first list, then read the second: it holds what UPPCS has not used yet.
First, the concept
Semiconductors lie between conductors and insulators in electrical behaviour. Adding small amounts of impurities changes the available charge carriers. A diode favours one current direction; a transistor can control or amplify a signal.
Devices convert energy rather than create it. A solar cell converts light to electricity, a battery uses chemical reactions, and a speaker turns electrical signals into vibrations. Distinguish energy conversion from voltage or current conversion.
✅ Already asked (19)
Semiconductors
- Silicon and germanium · Common elemental semiconductors used in electronic devices.
- Heating a semiconductor · For an intrinsic semiconductor, conductivity increases and resistance decreases as temperature rises.
- Diode · A junction diode conducts much more easily in forward bias than reverse bias.
- Transistor · Used as an amplifier or electronic switch.
- Integrated circuit · Many electronic components are made together on a semiconductor chip.
Current and light devices
- Rectifier · Converts alternating current into direct current.
- Inverter · Converts direct current into alternating current.
- Mobile charger · Reduces supply voltage and converts AC into regulated DC for charging.
- LED · Emits light when suitable current passes through a semiconductor junction.
- Photoelectric smoke alarm · Smoke scatters light towards a detector in a common optical design.
- Laser · Stimulated emission produces a highly directional beam with strong coherence.
Energy conversions
- Solar cell · Converts light directly into electrical energy by the photovoltaic effect.
- Dry cell · A common zinc-carbon cell uses a zinc container and a carbon rod terminal.
- Fuel cell · Converts the chemical energy of continuously supplied fuel and oxidant into electricity.
- Loudspeaker · Converts electrical signals into mechanical vibrations and sound.
- Microphone · Converts sound-induced vibrations into electrical signals.
- Automatic mechanical watch · Wrist movement winds its mainspring; a conventional quartz watch usually uses a battery.
- Thermocouple · Different-metal junctions at different temperatures can generate a voltage by the Seebeck effect.
Further electronic components
- LCD · Liquid crystals control transmitted light; a typical LCD needs a separate light source.
❌ Not asked yet (12)
Items marked 'asked in other exams' have come in UPSC or other state exams, not yet in UPPCS.
🔒 12 items not asked yet
Semiconductors: 3 · Current and light devices: 1 · Energy conversions: 1 · Further electronic components: 7
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⚠️ A rectifier converts AC to DC; an inverter converts DC to AC. A solar cell uses light, not heat alone.
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