SSC CGL - Detailed Guide 2025
Self-Paced Course
Daily Life Applications of Physics
Reference: Lucent GK, NCERT Class 6–12
1. Inventions and Inventors
| Invention | Inventor | Year |
|---|---|---|
| Electric Bulb | Thomas Edison | 1879 |
| Telephone | Alexander Graham Bell | 1876 |
| Radio | Guglielmo Marconi | 1895 |
| Television | John Logie Baird | 1927 |
| X-ray | Wilhelm Roentgen | 1895 |
| Thermometer (Mercury) | Gabriel Fahrenheit | 1714 |
| Steam Engine | James Watt | 1765 (Improved) |
| Transformer | Michael Faraday | 1831 (Concept) |
| Dynamite | Alfred Nobel | 1867 |
| Laser | Theodore Maiman | 1960 |
| Atomic Bomb (Theory) | Albert Einstein (E = mc²) | 1938 |
Focus on important practical inventions and associated physicists/inventors.
2. Electricity in Household
| Component | Description |
|---|---|
| AC Supply | Supplied by power grid (India: 230 V, 50 Hz AC) |
| Fuse | Safety device that melts when current exceeds limit |
| Circuit Breaker (MCB) | Automatically cuts off current in overload situations |
| Earthing | Prevents electric shock by directing leakage current to the ground |
| 3-Pin Plug | Live, Neutral, and Earth pins for safety |
| Parallel Circuit | Used in homes to ensure independent working of appliances |
| Electric Meter | Measures energy consumed in kilowatt-hours (kWh or unit) |
- Always use appropriate wire thickness based on appliance rating
- Earth wire (green) ensures safety in case of insulation failure
Electricity bills are based on units consumed:
1 unit = 1 kilowatt-hour = 1000 W × 3600 s = 3.6 × 10⁶ J
3. Working Principles of Common Appliances
| Appliance | Principle Used | Key Component |
|---|---|---|
| Microwave Oven | Electromagnetic waves (microwaves) excite water molecules → heat | Magnetron |
| Refrigerator | Heat pump: removes heat from inside and releases outside | Compression, Expansion, Coolant |
| Air Conditioner | Similar to refrigerator; cools air & controls humidity | Compressor, Evaporator, Fan |
| Electric Iron | Joule heating: I²R | Thermostat controls temperature |
| Induction Cooker | Electromagnetic induction → eddy current in vessel | Coil under ceramic plate |
| CFL & LED Bulbs | CFL: ionized gas → UV → visible
light LED: electrons recombine in semiconductor |
Gas discharge / Diode |
| Electric Fan | Electric motor (AC/DC) rotates blades | Electromagnetic induction |
| Washing Machine | Timer-based motor control, spinning drum mechanism | Electric motor, sensors |
Heat-based appliances (iron, geyser, oven) use high resistance wires for controlled heating
Magnetic and electric motors are fundamental to daily electronics
Developed By Jan Mohammad
Next
Start Your SSC CGL Journey Now!
Join Courage Library to experience disciplined study and expert support.
Be a Couragian!