Physics & Chemistry Fundamentals
Science & Technology – Exam Preparation
Introduction: Understanding Science Fundamentals
Physics and Chemistry form the foundation of scientific knowledge — explaining how matter behaves, how forces act, and how energy transforms.
In Delhi Police and SSC exams, questions often test basic principles, applications in daily life, and important discoveries.
A. Fundamental Concepts - Physics
1. Laws of Motion (Newton's Laws)
| Law | Statement | Example |
|---|---|---|
| 1st Law (Inertia) | A body remains at rest or in uniform motion unless acted upon by an external force. | Seat jerk when bus starts suddenly. |
| 2nd Law (Force) | Force = Mass × Acceleration (F = ma) | Kicking a ball harder → more acceleration. |
| 3rd Law (Action-Reaction) | Every action has an equal and opposite reaction. | Gun recoils backward when fired. |
2. Law of Gravitation
| Aspect | Details |
|---|---|
| Discovered by | Sir Isaac Newton |
| Formula | F = G m₁m₂ / r² |
| Meaning | Every object attracts every other object with a force directly proportional to their masses and inversely proportional to the square of the distance between them. |
3. Laws of Thermodynamics
| Law | Description |
|---|---|
| Zeroth Law | Basis of temperature measurement. |
| First Law | Energy can't be created or destroyed (Law of Energy Conservation). |
| Second Law | Heat flows from hot to cold naturally. |
| Third Law | At absolute zero (0 K), entropy becomes minimum. |
4. Light, Sound, and Energy Basics
| Concept | Fact / Example |
|---|---|
| Speed of Light | 3 × 10⁸ m/s (in vacuum) |
| Reflection | Bouncing of light (mirror) |
| Refraction | Bending of light (water glass effect) |
| Sound Speed in Air | 343 m/s (at 25°C) |
| Echo | Sound reflection (time gap ≥ 0.1 s) |
B. Chemistry - Fundamentals
1. Atomic Structure
| Discovery | Scientist | Year |
|---|---|---|
| Atomic Theory | John Dalton | 1808 |
| Electron | J.J. Thomson | 1897 |
| Proton | E. Goldstein | 1886 |
| Neutron | James Chadwick | 1932 |
| Nucleus | Ernest Rutherford | 1911 |
| Modern Model | Niels Bohr | 1913 |
2. Periodic Table
| Aspect | Details |
|---|---|
| Invented by | Dmitri Mendeleev (1869) |
| Modern Table (by Atomic Number) | Henry Moseley |
| Total Groups | 18 |
| Total Periods | 7 |
| Noble Gases | Group 18 (He, Ne, Ar, Kr, Xe, Rn) |
3. Chemical Reactions
| Type | Example |
|---|---|
| Combination | H₂ + Cl₂ → 2HCl |
| Decomposition | 2H₂O → 2H₂ + O₂ |
| Displacement | Zn + CuSO₄ → ZnSO₄ + Cu |
| Neutralization | Acid + Base → Salt + Water |
C. Modern Physics
1. Nuclear Physics
| Concept | Description |
|---|---|
| Nucleus | Contains protons & neutrons |
| Nuclear Fission | Splitting of heavy atoms (Uranium-235 → Atomic Bombs & Reactors) |
| Nuclear Fusion | Joining of light atoms (Hydrogen → Helium, in the Sun) |
2. Radioactivity
| Type | Emitted Particle | Penetration |
|---|---|---|
| Alpha (α) | Helium nucleus (2p + 2n) | Low |
| Beta (β) | Electron | Medium |
| Gamma (γ) | Electromagnetic waves | Very High |
3. Particle Physics
| Particle | Description |
|---|---|
| Basic Particles | Proton, Neutron, Electron |
| Subatomic Particles | Quarks, Neutrinos |
| Higgs Boson | Known as the "God Particle," discovered in 2012 at CERN |
D. Applied Chemistry
1. Polymers
| Polymer | Monomer | Use |
|---|---|---|
| Polyethylene (PE) | Ethylene | Plastic bags |
| Polystyrene | Styrene | Packaging |
| Teflon | Tetrafluoroethylene | Non-stick cookware |
| Nylon | Hexamethylene diamine + Adipic acid | Fabrics, ropes |
2. Alloys
| Alloy | Constituents | Use |
|---|---|---|
| Brass | Copper + Zinc | Musical instruments |
| Bronze | Copper + Tin | Coins, statues |
| Steel | Iron + Carbon | Construction |
| Solder | Lead + Tin | Joining metals |
Practice Questions (Delhi Police PYQ-style)
Who discovered the Law of Gravitation?
Options: A) Galileo B) Newton C) Einstein D) Kepler
Category: Physics
Show Answer
B) Isaac Newton
Which of the following is a thermodynamic law?
Options: A) Law of Inertia B) Law of Heat Flow C) Law of Cooling D) Boyle's Law
Category: Physics
Show Answer
B) Law of Heat Flow (Second Law of Thermodynamics)
The discovery of the neutron was made by —
Options: A) Chadwick B) Bohr C) Thomson D) Rutherford
Category: Chemistry
Show Answer
A) James Chadwick
The reaction between acid and base is called —
Options: A) Displacement reaction B) Neutralization reaction C) Decomposition reaction D) Oxidation reaction
Category: Chemistry
Show Answer
B) Neutralization reaction
Which gas is used in fertilizers?
Options: A) Nitrogen B) Oxygen C) Hydrogen D) Carbon Dioxide
Category: Chemistry
Show Answer
A) Nitrogen
Teflon is a polymer used for —
Options: A) Making tyres B) Non-stick coating C) Battery making D) Insulation only
Category: Chemistry
Show Answer
B) Non-stick coating
Quick Revision – One Line Memory
| Concept | Key Fact |
|---|---|
| Laws of Motion | Newton's Three Laws |
| Gravitation | F = Gm₁m₂ / r² |
| Thermodynamics | Energy conservation & heat flow |
| Atomic Structure | Thomson → Rutherford → Bohr |
| Periodic Table | Mendeleev (1869), 18 groups |
| Radioactivity | α, β, γ rays (Becquerel, Curie) |
| Polymers | Nylon, Teflon, Polyethylene |
| Fertilizers | N–P–K essential |
| Electricity | V = I × R (Ohm's Law) |
Exam Tricks & Mnemonics
Physics Trick:
"Newton's Laws: Inertia → Force → Reaction (IFR)"
Chemistry Trick:
"Atomic Discoveries: T–G–C–R–B (Thomson, Goldstein, Chadwick, Rutherford, Bohr)"
Radioactivity Trick:
"Alpha Heavy, Beta Light, Gamma Bright"
Nuclear Physics Trick:
"Fission Splits, Fusion Joins"
Chemical Reactions Trick:
"CDDN – Combine, Decompose, Displace, Neutralize"
Revision & Exam Points
Final Concept Recap
Master Science & Technology for all Competitive Exams!
Join Courage Library for complete study resources and expert guidance.
Be a Couragian!