General Physics & Everyday Chemistry

🎯 PYQs — Physics & Chemistry (Moderate Frequency)

Most Asked Topics:

• Newton's Laws applications
• Pressure and altitude effects
• Doppler Effect
• TIR and optical fibers
• Plastics types

Common Traps:

• ❌ Speed of sound higher in solids (not gases)
• ❌ Centrifugal force is apparent/pseudo (not real)
• ❌ Water is densest at 4°C (not 0°C)

1. Mechanics

Scalar vs Vector Quantities

Cue Words	Notes
Distinguish between Scalar and Vector quantities with examples.	Scalar Quantities: Magnitude only. Examples: Distance, Speed, Mass, Time. Vector Quantities: Magnitude + Direction. Examples: Displacement, Velocity, Force, Acceleration.

Key Kinematic Terms

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Define Velocity, Acceleration, Momentum, Force, and the Law of Conservation of Momentum.

Velocity ($v$): Rate of change of displacement ($v = \Delta s/\Delta t$; m/s). Acceleration ($a$): Rate of change of velocity ($a = \Delta v/\Delta t$; m/s²). Momentum ($P$): Mass $\times$ Velocity ($P = mv$; kg·m/s). Force ($F$): Push or pull causing acceleration ($F = ma$; Newton). Law of Conservation of Momentum: Total momentum remains constant in an isolated system (no external force) (e.g., escaping a frozen lake by throwing a bag in the opposite direction).

Newton's Laws of Motion

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State Newton's three laws of motion with everyday applications.

First Law (Inertia): A body remains at rest or in uniform motion unless acted upon by an external force (e.g., book on a table staying still). Second Law ($F=ma$): Acceleration is directly proportional to force and inversely proportional to mass (e.g., car accelerating faster with a stronger push). Third Law (Action-Reaction): Every action has an equal and opposite reaction (e.g., rocket propulsion).

Friction & Contact Mechanics

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Explain factors causing friction, contact mechanics, friction types, and methods to reduce friction.

Friction Factors: Microscopic surface irregularities, molecular adhesion, normal load, and material properties. Contact Mechanics: Real Contact Area: True microscopic touching area (much smaller than apparent area). Apparent Contact Area: Macroscopic visible touching region. Types of Friction: Static: Force to overcome to initiate motion (highest). Kinetic (Sliding): Opposes sliding motion between surfaces. Rolling: Opposes rolling motion (lowest friction). Friction Control: Ball Bearings: Reduce the effective area of contact by converting sliding into rolling motion. Lubrication: Oils, grease, or solid lubricants (graphite, molybdenum disulfide - MoS₂). Aerodynamic Streamlining: Reduces fluid drag. Materials: Teflon (PTFE), nylon, acetal.

Circular Motion & Centrifugal Force

Cue Words	Notes
Distinguish centripetal and centrifugal forces and list their applications.	Centripetal Force: Real force directed toward the center of a circular path ($F = mv^2/r$). Centrifugal Force: Apparent outward force arising from inertia (a pseudo/apparent force, not real). Applications: Cream separation (skimming milk), banking of curved roads, Earth's oblate shape, laboratory centrifuges, and ocean tides (in conjunction with gravity).

Airplane Lift

Cue Words	Notes
How does Bernoulli's Principle explain airplane lift?	Airplane Lift: Airplane lift exploits pressure differences. Faster air flow over the curved top surface creates low pressure (suction), while the bottom surface maintains higher pressure, generating upward lift force (Bernoulli's principle).

2. Advanced Sensors & Energy Harvesting

Energy Harvesting

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Define energy harvesting, its ambient sources, and applications.

Energy Harvesting: Capturing ambient energy (light, heat, vibration) to generate usable electricity. Sources: Thermoelectric: Uses waste heat via Seebeck effect. Piezoelectric: Uses mechanical vibrations or human motion (e.g., smart floors/shoes). Triboelectric Nanogenerators (TENGs): Converts low-frequency mechanical energy into electricity via contact electrification. Applications: IoT sensors, wearables, medical implants, smart building tech.

Modern Sensing Technologies

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Detail MEMS sensors, accelerometer uses, nano-sensors, and vibration/acoustic sensors.

MEMS (Micro-Electrical-Mechanical Systems): Micro-scale machines on a chip. Accelerometer Applications: Deploying airbags in car crashes, rotating smartphone displays, and turning off hard drives during accidental falls. Nano-sensors: Vast surface-area-to-volume ratio for targeted pathogen detection and precision agriculture. Acoustic Sensors: Bridge monitoring and early earthquake warning systems (detecting P-waves).

3. Pressure

Pressure Basics

Cue Words	Notes
State the pressure formula, SI unit, and factors affecting pressure.	Pressure Formula: $P = F/A$ (Force per unit area). SI Unit: Pascal (Pa) = 1 N/m² ($1 \text{ atm} = 1.013 \times 10^5 \text{ Pa}$). Factors: Directly proportional to force and density of fluid; increases with depth in liquids; inversely proportional to area of contact.

Pressure Applications

Cue Words	Notes
Outline everyday applications of pressure differences.	Applications: Straw drinking: Low pressure inside straw; atmospheric pressure pushes liquid up. Hydraulic lifts: Small force on small piston → Large force on large piston. Land/Sea Breeze: Differential heating creates pressure differences. Cloud formation: Low pressure → Rising air → Cooling → Condensation.

Pressure & Altitude

Cue Words	Notes
How do pressure and altitude interact? Explain boiling point changes and pressure cooker mechanics.	Altitude Interaction: Atmospheric pressure decreases with altitude because there is less air column above. Boiling Point: Decreases at higher altitudes ($<100^\circ\text{C}$ on mountain tops). Pressure Cooker: Increases internal pressure, raising the water's boiling point, which cooks food faster. The temperature reached depends mainly on the area of the lid hole and the weight of the lid.

4. Fluid Dynamics

Flow Types

Cue Words	Notes
Compare Laminar and Turbulent fluid flow.	Laminar Flow: Smooth, parallel layers of fluid; low Reynolds number (e.g., blood flow in capillaries). Turbulent Flow: Chaotic, mixing fluid flow; high Reynolds number (e.g., river rapids).

Diffusion, Osmosis, Dialysis

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Distinguish between Diffusion, Osmosis, and Dialysis.

Physical Transport Mechanisms: Diffusion: Net movement of particles from high to low concentration (e.g., oxygen diffusing into blood in lungs). Osmosis: Movement of water molecules through a semipermeable membrane from low solute to high solute concentration (e.g., plant root absorption). Dialysis: Selective movement of solutes based on particle size across a semipermeable membrane (e.g., kidney dialysis).

Surface Tension & Capillarity

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Explain surface tension, capillarity, concave vs convex menisci, anomalous density of water, and wettability.

Surface Tension: Liquid surface behaves like a stretched elastic membrane due to cohesive forces. Capillarity: Rise or fall of liquid in narrow tubes. Concise: Concave meniscus (e.g., water) rises because Adhesion > Cohesion; Convex meniscus (e.g., mercury) falls because Cohesion > Adhesion (e.g., kerosene lamp wicks, water transport in xylem). Anomalous Density: Water reaches maximum density at 4°C. Ice floats, insulating liquid water underneath and preserving aquatic life. Wettability: Depends on solid surface energy vs liquid surface tension. Hydrophilic surfaces spread water, hydrophobic surfaces form droplets (lotus-effect). Nano-Water Treatment: Iron oxide nanoparticles remove heavy metals; silver nanoparticles kill microbes; nano-bubbles prevent algal growth.

5. Heat & Thermodynamics

Temperature vs Heat

Cue Words	Notes
Compare Temperature and Heat: definitions, units, and thermodynamic nature.	Temperature: Measure of average kinetic energy of molecules; intensive property (independent of amount); units in Kelvin (K) or Celsius (°C). Heat: Energy transferred due to a temperature difference; extensive property (depends on amount); units in Joules (J).

Specific Heat Capacity

Cue Words	Notes
Define specific heat capacity and explain the ecological/biological importance of water's high specific heat.	Specific Heat Capacity: Heat required to raise the temperature of 1 kg of a substance by 1°C. Water's High Specific Heat: Moderates global climate by storing/releasing heat slowly, keeps coastal regions warmer in winter, and acts as a thermal shield to stabilize human body temperature.

Special Properties of Water

Cue Words	Notes
List the special thermal properties of water and define latent heat.	Water's Key Properties: Maximum density at 4°C, ice floating, and high latent heat. Latent Heat: Heat energy absorbed or released during a phase change without changing the temperature (e.g., latent heat of fusion and latent heat of vaporization).

Heat Transfer & Radiative Cooling

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Detail the three modes of heat transfer, black body radiation, passive radiative cooling, and nano-thermal physics.

Heat Transfer: Conduction (direct contact), Convection (fluid movement like motor car radiators), and Radiation (no medium needed). Black Body Radiation: Ideal emitter/absorber; peak wavelength shifts to shorter wavelengths as temperature rises. Radiative Cooling: Passive cooling where surfaces emit heat as infrared radiation to outer space (e.g., white-painted roofs). Nano-Scale Heat: Conducted via phonons. Heat sinks use graphene or carbon nanotubes (CNTs) for fast dissipation in microcircuits.

Cryogenics

Cue Words	Notes
Define cryogenics and list its major applications.	Cryogenics: Study of materials at extremely low temperatures (below -150°C). Applications: Liquid hydrogen/oxygen rocket propellants, cooling MRI superconducting magnets, cryopreservation of biological tissues, LNG transport, and cryosurgery.

6. Optics & EM Radiation

Electromagnetic (EM) Spectrum

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Order the EM spectrum by energy, and detail visible light, IR, and UV properties.

EM Spectrum Order (Lowest to Highest Energy): Radio → Microwave → Infrared → Visible (Red to Violet) → Ultraviolet (UV) → X-rays → Gamma rays. Infrared (IR): Emitted by hot bodies; used in night vision, remote controls, and motion sensors. Ultraviolet (UV): UVA (deep skin penetration), UVB (sunburn/DNA damage), UVC (most energetic, ozone-absorbed). UV radiation inactivates microorganisms in water purification but does not remove odour/turbidity. Albedo: High albedo reflects radiation (cooling), low albedo absorbs radiation (warming).

Lighting Technologies

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Compare Sodium Vapour, LED, OLED, and QLED lighting technologies.

Lighting Framework: Sodium Vapour: Omnidirectional, yellow monochromatic light; high efficiency, poor color rendering. LED: Directional light via electron-hole recombination; broad-spectrum, long life. OLED: Self-emissive organic materials (no backlight needed); can be made flexible/transparent. QLED: Inorganic quantum dots with LED backlight; brighter and longer lasting than OLED, lower color accuracy.

Reflection

Cue Words	Notes
State the laws of reflection and their applications.	Laws of Reflection: Angle of incidence equals angle of reflection; incident, reflected, and normal rays lie in the same plane. Applications: Flat/curved mirrors, solar cookers, periscopes.

Refraction

Cue Words	Notes
Explain refraction, refractive index, and lens corrections.	Refraction: Bending of light when crossing mediums of different optical densities (denser slows/bends toward normal, rarer speeds/bends away). Refractive Index ($n$): $n = c/v$ (speed of light in vacuum vs medium). Lenses: Convex: Converging lens; corrects hyperopia (farsightedness). Concave: Diverging lens; corrects myopia (nearsightedness).

Total Internal Reflection (TIR)

Cue Words	Notes
Define Total Internal Reflection (TIR) and list its applications.	TIR: Occurs when light travels from a denser to a rarer medium and the angle of incidence exceeds the critical angle. Applications: Optical fiber communications, diamond brilliance, and mirages.

Dispersion

Cue Words	Notes
What is dispersion? Explain VIBGYOR and rainbow formation.	Dispersion: Splitting of white light into its component colors by a prism. Wavelengths (VIBGYOR): Violet bends the most (shortest wavelength), Red bends the least (longest wavelength). Rainbow: Combined effect of dispersion, refraction, and internal reflection in water droplets.

Doppler Effect

Cue Words	Notes
Define the Doppler Effect and outline its applications in astronomy and technology.	Doppler Effect: Change in frequency of a wave relative to an observer who is moving relative to the wave source (approaching has higher pitch/frequency; receding has lower). Applications: Redshift/blueshift in astrophysics, Doppler ultrasound, radar speed detection guns.

7. Sound

Sound Basics

Cue Words	Notes
Detail sound properties: wave nature, speed in different phases, and human hearing range.	Sound Waves: Longitudinal mechanical waves; require a medium (cannot travel in vacuum). Speed of Sound: Solids > Liquids > Gases (speed in air $\approx$ 343 m/s). Hearing Range: 20 Hz to 20,000 Hz for healthy humans.

Key Sound Terms

Cue Words	Notes
Define Hypersonic speed, Mach Number, Sonic Boom, Ultrasound, and Infrasound.	Sound Properties: Hypersonic: Speeds exceeding Mach 5 (5 times the speed of sound). Mach Number: Ratio of object speed to the speed of sound in the surrounding medium. Sonic Boom: Shock waves created when an object travels faster than sound. Ultrasound: Frequencies above 20,000 Hz (used in medical scans, SONAR). Infrasound: Frequencies below 20 Hz (e.g., earthquakes, elephant communication).

Sound Applications

Cue Words	Notes
List applications of SONAR, medical ultrasound, and acoustic levitation.	Applications: SONAR: Sound Navigation and Ranging used by submarines to map/detect underwater objects. Medical Scan: High-frequency sound waves image soft tissues without radiation. Acoustic Levitation: Using intense sound waves to counteract gravity and levitate small objects.

8. Electricity & Magnetism

Basic Electrical Concepts

Cue Words	Notes
Define electric charge, current, voltage, resistance, and Ohm's Law.	Electrical Terms: Charge ($Q$): Physical property of matter causing EM force (Coulomb). Current ($I$): Rate of flow of charge (Ampere). Voltage ($V$): Electric potential difference (Volt). Resistance ($R$): Opposition to current flow (Ohm). Ohm's Law: $V = I \times R$.

Circuit Types

Cue Words	Notes
Compare Series and Parallel circuits and explain home wiring.	Series Circuits: Same current through all components; voltage divides. Parallel Circuits: Same voltage across all components; current divides. Home Wiring: Always connected in parallel so appliances can operate independently at the same voltage.

Magnetism & Electromagnetism

Cue Words	Notes
Define magnetic fields, electromagnetism, Faraday's Law, and list applications.	Concepts: Moving charges produce magnetic fields (Tesla), and changing magnetic flux induces electromotive force (Faraday's Law). Applications: Electric motors, generators, transformers, MRI machines, and Maglev trains.

Natural Phenomena

Cue Words	Notes
Explain Auroras and Lightning.	Aurora: Solar charged particles interacting with Earth's magnetic field near polar regions. Lightning: High-voltage electrical discharge between cloud layers or clouds and the ground.

9. Particle & Astroparticle Physics

Standard Model & Fundamental Particles

Cue Words	Notes
Recall quarks, leptons, force-carrying bosons, and the limits of the Standard Model.	Fermions: Quarks (building blocks of hadrons like protons/neutrons) and Leptons (electrons, neutrinos). Bosons: Gluons (strong force carrier) and Higgs Boson (gives mass to particles). Incompleteness: Standard Model does not account for Gravity, Dark Matter, or Matter-Antimatter asymmetry.

Fundamental Forces of Nature

Cue Words	Notes
Name and compare the four fundamental forces of nature: carriers, ranges, and strengths.	Forces Comparison: Strong Nuclear: Binds protons/neutrons in nucleus; strongest force; subatomic range; carrier: Gluons. Electromagnetic: Acts on charged particles; infinite range; carrier: Photons. Weak Nuclear: Causes radioactive beta decay; subatomic range (shortest); carrier: W, Z bosons. Gravitational: Universal mass attraction; weakest force; infinite range; carrier: Graviton (theoretical).

Neutrinos & Observatories

Cue Words	Notes
Detail neutrinos, neutrino oscillations, Cherenkov radiation, and the INO project.	Neutrinos: Massless/nearly massless ghost particles interacting only via weak nuclear force and gravity. Change flavor (oscillate) during travel, proving they have mass. Cherenkov Radiation: Blue light emitted when charged particles exceed the phase velocity of light in a medium. Observatories: IceCube (Antarctica), Super-Kamiokande (Japan), and the proposed India-based Neutrino Observatory (INO) at Theni, TN (Iron Calorimeter detector).
Compare JUNO, INO, and KATRIN in neutrino research.	JUNO (China): Jiangmen Underground Neutrino Observatory, now complete and operational; has precisely measured the θ-12 neutrino oscillation angle, working toward resolving the neutrino mass-ordering problem. INO (India): Stalled for years — its 50-kilotonne detector needed a purpose-built mountain cavity (proposed at Theni, Tamil Nadu) rather than an existing facility, driving cost/feasibility concerns. KATRIN (Germany): Karlsruhe Tritium Neutrino experiment; 200-tonne spectrometer measures the beta-decay electron energy spectrum of tritium to directly bound neutrino mass, since oscillation experiments reveal only mass differences, not absolute mass. Neutrino astronomy began in 1987 with detection of Supernova 1987A neutrinos, arriving ~3 hours before its light.

CERN & Large Hadron Collider

Cue Words	Notes
Detail the Large Hadron Collider (LHC) and its primary detector experiments.	LHC: World's largest particle accelerator (27-km ring) at CERN, Geneva. Experiments: ATLAS & CMS (discovered Higgs), ALICE (heavy ions), LHCb (matter-antimatter), CLOUD (cosmic rays/climate).

10. Chemistry in Everyday Life

Medicines & Drugs

Drug Classification

Cue Words	Notes
Classify common medicines: Analgesics, Antipyretics, Antibiotics, Antacids, Antihistamines, and Tranquilizers.	Pharmaceutical Database: Analgesics: Pain relief (Aspirin, Ibuprofen, Morphine). Antipyretics: Fever reduction (Paracetamol). Antibiotics: Kill bacteria (Penicillin, Azithromycin). Antacids: Neutralize stomach acid (Magnesium hydroxide, Omeprazole). Antihistamines: Block histamine in allergies (Cetirizine, Fexofenadine). Tranquilizers: Anxiety/tension reduction (Alprazolam, Clonazepam).

Chemicals in Food

Food Additives

Cue Words	Notes
Outline food additives: Preservatives, Artificial Sweeteners, and Antioxidants.	Food Chemistry: Preservatives: Prevent spoilage (Sodium benzoate, Potassium sorbate). Artificial Sweeteners: Low-calorie sweets (Aspartame - 100x sweeter than sugar, Sucralose, Stevia). Antioxidants: Prevent food oxidation (BHA, BHT).

Chemicals of Concern

Cue Words	Notes
Explain health concerns of Aspartame, Titanium Dioxide, BPA, and Triclosan.	Concern Database: Aspartame: Diet foods; metabolized providing calories but used in minute amounts. Titanium Dioxide: Candies, toothpaste; nanoparticle safety concerns. BPA (Bisphenol A): Plastic containers; endocrine disruptor. Triclosan: Soap, toiletries; linked to long-term exposure toxicity.

Cleansing Agents

Soaps vs Detergents

Cue Words	Notes
Compare soaps and detergents: composition, hard water behavior, and biodegradability.	Cleansing Chemistry: Soaps: Sodium/Potassium salts of fatty acids; form scum in hard water; easily biodegradable; less environmental harm. Detergents: Ammonium/Sulphonate salts; work effectively in hard water; often non-biodegradable; can cause water pollution.

Plastics

Plastic Types

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Classify plastics by recycling codes: PET, HDPE, PVC, LDPE, PP, and PS.

Recycling Codes: PET (1): Water bottles; easily recycled. HDPE (2): Milk jugs, pipes; easily recycled. PVC (3): Pipes, flooring; difficult to recycle (toxic). LDPE (4): Plastic bags, wraps; difficult to recycle. PP (5): Bottle caps, straws; moderate to recycle. PS (6): Thermocol, cups; hard to recycle. Titanium Dioxide Nanoparticles (TiO₂): Used in coatings/paints for UV protection, photocatalytic self-cleaning, and whiteness.

Environmental Chemicals

Pollutants of Concern

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Identify PFAS, Glyphosate, Oxybenzone, Formaldehyde, and Microplastics.

Environmental Toxicology: PFAS ("Forever Chemicals"): Non-stick cookware, firefighting foam; persistent in environment and body. Glyphosate: Widely used herbicide; potential carcinogen. Oxybenzone: Common chemical sunscreen filter; associated with coral reef bleaching. Formaldehyde: Industrial glue, furniture; human carcinogen. Microplastics: Degraded plastic fragments; widespread marine and food chain pollution.

High-Yield S&T Rapid Revision: Top UPSC Traps

1. PSLV: Utilizes four stages (solid-liquid-solid-liquid), whereas GSLV uses three stages (solid-liquid-cryogenic) (ISRO).
2. Covishield: Developed on a viral vector platform (adenovirus), not mRNA (ICMR).
3. Quantum Computing: Classical bits are strictly 0 or 1, while qubits exploit superposition to exist in multiple states simultaneously (DST).
4. Web 3.0: Decentralized web architecture enabling user data ownership via blockchain and DAOs (MeitY).
5. NFC: Near Field Communication operating range is limited to approximately 10 centimeters, not 1 meter (DoT).
6. Licensed vs. Indigenous: Systems built in India under license/ToT—specifically Su-30 MKI (HAL Nasik, Russian origin), T-90S Bhishma (HVF Avadi, Russian origin), and K9 Vajra-T (L&T Hazira, South Korean origin)—are not indigenous designs (common matching trap).
7. Submarine Propulsion Classes: SSBN (nuclear ballistic, e.g., Arihant) vs. SSN (nuclear attack, e.g., leased Chakra) vs. SSK (diesel-electric conventional, e.g., Kalvari). INS Chakra was strictly leased from Russia, not owned or built domestically.
8. AWACS & Radar Platforms: DRDO Netra is a co-developed/hybrid system (Indian radar on Brazilian Embraer jet frame), whereas Phalcon is imported (Israeli radar on Russian airframe).
9. BrahMos: A joint venture between India (DRDO) and Russia, but is not part of the IGMDP (Prithvi, Agni, Trishul, Akash, Nag).

• Section 3(d) of the Indian Patent Act disallows ever-greening of patents (renewal via minor product modifications); the Novartis Glivec (cancer drug) case tested this provision.
• Ever-greening is a practice by pharma companies to extend patent protection beyond the standard 20-year term.
• Traditional Knowledge Digital Library (TKDL) is India's initiative to prevent biopiracy/misappropriation of traditional medicinal knowledge at international patent offices.
• TKDL's origin traces to India's successful revocation of a USPTO patent on the wound-healing properties of turmeric.
• In 2005, a TKDL expert group estimated about 2000 wrong patents on Indian systems of medicine were granted internationally every year.
• A Utility Model protects inventions like a patent but for a shorter term (6-15 years) and does not require an inventive step, only novelty and industrial applicability.
• A trademark is initially registered for 10 years from the date of filing of application.
• Under India's Designs Act, 2000, an industrial design registration has maximum validity of 15 years.
• A Geographical Indication (GI) is registered for 10 years, renewable for further periods of 10 years at a time.
• Trade secrets are confidential-information IP rights (formulae, recipes, processes) that remain valid as long as they are not independently discovered.
• An organometallic compound contains a carbon-metal bond, combining properties of metals and organic molecules; many are air/moisture sensitive and can act as catalysts.