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UPPCS Physics Gap Sheet: Electricity and Electrical Safety.
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First, the concept
Current is the flow of electric charge. A source supplies energy to move charge; it does not create electrons. Resistance limits current, and electrical energy can become heat, light or mechanical motion.
Home appliances are connected in parallel so each gets the supply voltage. A fuse or circuit breaker interrupts excessive current; earthing provides a safe fault-current path. Their protective functions are related but different.
✅ Already asked (19)
Charge and circuits
- Electric potential · A scalar quantity; electric field is a vector.
- Silver conductor · Among common metals at room temperature, silver conducts electricity best.
- Series connection · The same current passes through all components; a break stops the whole circuit.
- Parallel domestic wiring · Each appliance gets the same supply voltage and can be switched independently.
- Ideal cell · Its internal resistance is zero.
- Electricity billing unit · One unit is one kilowatt-hour of electrical energy.
Heating and energy conversion
- Tungsten filament · Its high melting point suits incandescent lamp filaments.
- Nichrome heater · High resistivity and oxidation resistance make nichrome useful in heating elements.
- Electric motor · Converts electrical energy into mechanical energy.
- Generator and dynamo · Convert mechanical energy into electrical energy; they do not create charge.
- Transformer · Changes AC voltage by mutual induction; steady DC does not give continuous transformer action.
- Low-voltage motor heating · Some loaded motors draw excessive current at low voltage and may overheat.
Protection
- Fuse · A suitable fusible wire melts when excessive current heats it; it is connected in series in the live wire.
- Earthing · A low-resistance earth path helps protect users when a metal casing becomes live.
- Three-pin plug · The earth pin is longer, so earth contact is made first and broken last.
- Lightning conductor · Provides a conductive path to earth for lightning current.
- Metal car in lightning · A closed metal body guides current around occupants; the rubber tyres are not the main protection.
Further circuit facts
- Capacitor storage · Stores electrical energy in an electric field; it is not a chemical battery.
- Superconductivity · Below a critical temperature, a superconductor has zero DC resistance and shows the Meissner effect.
❌ Not asked yet (12)
🔒 12 items not asked yet
Charge and circuits: 2 · Heating and energy conversion: 1 · Protection: 3 · Further circuit facts: 6
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⚠️ A kilowatt is power; a kilowatt-hour is energy. A fuse belongs in the live wire, not merely in the neutral wire.
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