⚡ 12th Std Physics Top 20 Three Mark Questions – Most Repeated (2025)
📚 Ace Your Public Exam with the Most Repeated 3-Mark Questions!
The 12th Physics Top 20 Three Mark Questions Guide is tailored for Tamil Nadu 12th Public Exam 2025 students aiming for high scores. It features chapter-wise, frequently repeated three-mark questions derived from previous year public exams, model tests, and textbook exercises. These high-scoring questions cover key definitions, concepts, and numerical problems, making them vital for exam preparation.
1. Galvanometer conversion (6 times)
- How is a galvanometer converted into an ammeter?
- How is a galvanometer converted into a voltmeter?
2. Parallel Plate Capacitor Energy Expression (5 times)
- Derive an expression for energy stored in a capacitor.
- Derive the expression for equivalent capacitance when capacitors are connected in parallel/ Series.
3. Fresnel vs. Fraunhofer Diffraction (4 times)
- Difference between Fresnel and Fraunhofer diffraction.
4. Brewster’s Law (4 times)
- State and prove Brewster’s law.
- State Snell’s law / law of refraction.
5. Biot-Savart’s Law (4 times)
- State and explain Biot-Savart law.
6. Drift Velocity and Current (4 times)
- Derive the relation between current and drift velocity.
7. De Broglie Wavelength (4 times)
- Derive an expression for the de Broglie wavelength of electrons.
8. Photoelectric Effect Laws (4 times)
- List out the laws of photoelectric effect.
9. Capacitance of Parallel Plate Capacitor (3 times)
- Obtain the expression for capacitance for a parallel plate capacitor.
- Calculate the capacitance of the capacitor in paralle and seies
10. Transformer Energy Loss (3 times)
- Mention various energy losses in a transformer.
11. Magnetic Field and Torque (3 times)
- Derive an expression for the torque experienced by a dipole due to a uniform electric field.
- Compute the torque experienced by a magnetic needle in a uniform magnetic field.
12. Lorentz Force (3 times)
- Give an account of magnetic Lorentz force.
- Write down the features of Lorentz Force.
- Obtain an expression for motional emf for Lorentz Force.
✅ Moderately Repeated Questions (2 times)
1. Gauss’s Law
- Obtain Gauss law from Coulomb’s law.
2. Spherical Mirror Relation (f and R)
- Derive the relation between f and R for a spherical mirror.
3. Seebeck Effect Applications
- What is the Seebeck effect? State the applications of the Seebeck effect.
4. Nicol Prism Discussion
- Discuss about Nicol prism.
5. De Morgan’s Theorem
- State and prove De Morgan’s first and second theorems.