Modern Physics Syllabus, Notes & Questions for Competitive Exams
Modern Physics is a branch of physics that explores the behavior of matter and energy at extremely small scales and at very high speeds. Unlike classical physics, which focuses on everyday phenomena, modern physics deals with concepts that emerged in the twentieth century, such as quantum physics and relativity.
At its core, modern physics investigates phenomena that classical physics cannot explain—like the dual nature of light and matter, and the ways in which space and time are affected by extreme gravity or velocity. These subjects continue to shape our understanding of the universe today.
Historically, the development of modern physics marked a major shift from previous scientific thought. While Isaac Newton and others established foundational laws for classical mechanics, new discoveries in the nineteenth and twentieth centuries revealed unexpected results at atomic and subatomic scales.
Core Branches of Modern Physics
Modern physics centers on two key areas: quantum physics and relativity. Quantum physics explores the discrete and probabilistic nature of energy and matter, while relativity describes how time, space, and gravity behave at immense speeds and around massive objects.
Quantum physics shows that particles like electrons and photons can behave both as waves and as particles. In contrast, relativity demonstrates that the passage of time and the measurement of space are not absolute, but depend on the observer's frame of reference.
| Concept | Description | Key Figures | Related Vedantu Resources |
|---|---|---|---|
| Quantum Physics | Studies the nature of matter and energy at atomic and subatomic scales. Introduces quanta and wave-particle duality. | Max Planck, Albert Einstein | Quantum Mechanics |
| Relativity | Explains how speed and gravity alter perceptions of time and space; includes special and general relativity. | Albert Einstein | Special Theory of Relativity |
| Atomic Structure | Investigates the makeup and behavior of atoms, including subatomic particles. | Niels Bohr, Ernest Rutherford | Atomic Physics |
Key Formulas in Modern Physics
| Formula | Concept | Meaning and Application |
|---|---|---|
| E = hν | Quantum of Energy | Energy (E) of a photon is the product of Planck’s constant (h) and frequency (ν). |
| λ = h/p | de Broglie Wavelength | A particle’s wavelength (λ) depends on Planck’s constant divided by the particle’s momentum (p). |
| E = mc2 | Mass-Energy Equivalence | Energy (E) is equal to mass (m) times the speed of light (c) squared. |
Examples and Conceptual Applications
Example 1: If a photon has a frequency of 6 × 1014 Hz, what is its energy?
E = 6.626 × 10-34 × 6 × 1014 = 3.976 × 10-19 Joules.
Example 2: What is the de Broglie wavelength of an electron with momentum 3.3 × 10-24 kg·m/s?
λ = 6.626 × 10-34 / 3.3 × 10-24 = 2.01 × 10-10 meters.
Stepwise Approach to Solving Modern Physics Problems
| Step | What To Do | Example |
|---|---|---|
| 1 | Identify what is given and what is to be found | Given photon frequency, find its energy |
| 2 | Choose the correct formula | Use E = hν |
| 3 | Substitute the values with correct units | h in J·s, ν in Hz |
| 4 | Calculate step by step | Multiply values and express the result in joules |
| 5 | Check if the answer is reasonable in context | Value should be a small number for a single photon |
Comparing Classical and Modern Physics
| Aspect | Classical Physics | Modern Physics |
|---|---|---|
| Scale | Daily life, macroscopic | Atomic, subatomic, and high-speed |
| Main Laws | Newton's Laws, Maxwell’s equations | Quantum mechanics, Relativity |
| Certainty | Deterministic | Probabilistic/statistical |
| Examples | Projectile motion, Sound waves | Photoelectric effect, Particle-wave duality |
Key Modern Physics Topics to Explore Further
- Photoelectric Effect
- Atomic Spectra
- Wave Particle Duality
- Mass-Energy Equivalence
- Relativity and Spacetime
- Quantum Mechanics
- Nuclear Fission and Nuclear Fusion
Take the Next Step in Modern Physics
Modern physics impacts how we understand the universe on the tiniest and grandest scales, with ideas ranging from photons to black holes. Practice questions, explore solved examples, and use reliable study resources to deepen your grasp of these transformative concepts.
For more in-depth study, visit topics such as quantum mechanics and special relativity.
FAQs on Modern Physics: Essential Concepts, Formulas & Examples for 2025
1. What is covered in modern physics?
Modern physics covers the study of atomic, subatomic, and fundamental particle phenomena that cannot be explained by classical physics.
Key topics include:
• Quantum mechanics (wave-particle duality, de Broglie wavelength)
• Photoelectric effect and Einstein’s photoelectric equation
• Atomic models (Bohr, Rutherford, Hydrogen atom)
• Radioactivity and nuclear physics (alpha, beta, gamma decay)
• Special relativity (mass-energy equivalence, E = mc2)
These concepts are crucial in class 12 and for JEE/NEET exams.
2. What is the difference between classical and modern physics?
The main difference is the scale and nature of phenomena each field explains.
• Classical physics studies macroscopic objects (motion, gravity, electricity) using deterministic laws like Newton’s.
• Modern physics addresses atomic/subatomic behavior and introduces probabilistic principles (quantum mechanics, relativity).
• Modern physics explains effects like photoelectric effect, atomic structure, relativity which classical physics cannot.
3. What are examples of modern physics?
Examples of modern physics include phenomena that require quantum theory or relativity to explain.
Common examples are:
• Photoelectric effect
• Wave-particle duality of electrons and photons
• Radioactive decay
• Nuclear fission and fusion
• Atomic spectra (Hydrogen spectrum)
• Special relativity (time dilation, E = mc2)
These are routinely asked in CBSE, JEE, and NEET exams.
4. What are the main branches of modern physics?
The two main branches are quantum physics and relativity.
• Quantum physics deals with particles at atomic and subatomic scales (quantum mechanics, photoelectric effect, atomic structure).
• Relativity (special and general) describes physics at extreme speeds, addressing time dilation and mass-energy relationships.
• Nuclear physics and particle physics are also key branches.
5. What are the key formulas used in modern physics?
Key modern physics formulas include:
• Einstein’s photoelectric equation: KEmax = hν – φ
• de Broglie wavelength: λ = h/p
• Energy–mass equivalence: E = mc2
• Binding energy: BE = (Δm)c2
• Bohr radius: a0 = 0.529 × 10-10 m
These are critical for exam preparation.
6. Can I skip modern physics for NEET?
It is not advisable to skip modern physics for NEET.
• Modern physics accounts for approximately 12–18 marks in NEET Physics.
• Topics like photoelectric effect, atomic nuclei, radioactivity are commonly tested.
• These topics are scoring due to formula-based and conceptual questions.
Covering modern physics can significantly boost your score.
7. How do I approach problem-solving in modern physics?
Follow these steps for solving modern physics numericals:
1. Read the problem and note the given and required values.
2. Select the appropriate formula (e.g., KEmax = hν – φ).
3. Convert all units to SI (eV to joules if needed).
4. Substitute values stepwise and solve.
5. Check your final answer for correct units.
Practice and reviewing solved examples strengthens understanding.
8. What is the photoelectric effect?
The photoelectric effect is the emission of electrons from a metal surface when light of suitable frequency falls on it.
• Demonstrates the particle nature of light (photons).
• Explained by Einstein, leading to the equation KEmax = hν – φ.
• Important for both board exams and entrance exams like JEE/NEET.
9. What is the de Broglie wavelength?
The de Broglie wavelength represents the wave nature of moving particles.
• Formula: λ = h/p, where h is Planck’s constant and p is momentum.
• Shows that electrons, protons, and other particles exhibit both wave and particle characteristics.
Used in explaining electron diffraction and quantum behaviors.
10. Why is modern physics important for JEE and NEET?
Modern physics contributes a significant portion of marks and involves scoring, formula-based questions.
• Typically, 15–23 marks in JEE and 12–18 marks in NEET come from modern physics.
• Questions are direct and often involve less calculation than classical mechanics.
• Mastery can greatly improve rank due to high accuracy rates.
11. What are common misconceptions in modern physics?
Common misconceptions include:
• Assuming classical laws always apply at atomic scales (they do not)
• Confusing photon energy (E = hν) with work function (φ)
• Mixing up particle and wave behaviors in quantum mechanics
• Misapplying formulas without unit conversion
Clarifying these helps avoid errors in exams.
12. Where can I find structured notes and practice questions for modern physics?
You can access modern physics notes, MCQs, and solved examples:
• On Vedantu’s Modern Physics topic page
• Through links to Quantum Mechanics, Photoelectric Effect, and Nuclear Physics
• In official JEE Main and NEET syllabus pages
These resources are aligned to the 2025 exam pattern for effective revision.
