Class 12 Physics: The 25 Guaranteed Derivations

Soumya Sir's Physics Class THE 25 GUARANTEED DERIVATIONS Class 12 Board Exam Essentials

Unit 1: Electrostatics

1. Electric Field: Axial & Equatorial Line ⭐⭐⭐⭐⭐

2. Gauss Law: Infinite Wire & Sheet ⭐⭐⭐⭐

3. Capacitance with Dielectric Slab ⭐⭐⭐⭐⭐

4. Energy Stored in Capacitor ($U=\frac{1}{2}CV^2$) ⭐⭐⭐

5. Potential Energy of Electric Dipole ($U = -pE \cos \theta$) ⭐⭐⭐

Unit 2: Current Electricity

6. Drift Velocity & Current ($I=neAv_d$) ⭐⭐⭐⭐

7. Wheatstone Bridge (Kirchhoff’s Laws) ⭐⭐⭐⭐⭐

Unit 3: Magnetism

8. Field on Axis of Circular Loop (Biot-Savart) ⭐⭐⭐⭐⭐

9. Force between Parallel Wires ⭐⭐⭐⭐

10. Torque on Current Loop (Magnetic Dipole) ⭐⭐⭐

Unit 4: EMI & AC

11. Mutual Inductance of Solenoids ⭐⭐⭐

12. AC Generator (Instantaneous EMF) ⭐⭐⭐⭐

13. Series LCR Circuit (Impedance Triangle) ⭐⭐⭐⭐⭐

Unit 6: Optics (High Weightage)

14. Lens Maker’s Formula ⭐⭐⭐⭐⭐

15. Refraction at Spherical Surface ⭐⭐⭐⭐

16. Combination of Thin Lenses in Contact ⭐⭐⭐⭐

17. Prism Formula ($\mu = \frac{\sin(A+\delta_m)/2}{\sin A/2}$) ⭐⭐⭐⭐⭐

18. Huygen’s Principle (Proof of Laws) ⭐⭐⭐⭐

19. YDSE: Fringe Width Expression ⭐⭐⭐⭐⭐

20. Diffraction Single Slit (Conditions) ⭐⭐⭐

Units 8 & 9: Modern Physics

21. Bohr’s Quantization (Radius/Energy) ⭐⭐⭐⭐⭐

22. De-Broglie Wavelength ⭐⭐⭐

23. B.E. per nucleon vs Mass Number Graph ⭐⭐⭐⭐

24. Nuclear Density (Constant Proof) ⭐⭐

25. Conductivity of Semiconductor ($\sigma = e(n_e\mu_e + n_h\mu_h)$) ⭐⭐⭐

💡 Pro-Tip for 5 Marks:
A Derivation is incomplete without a DIAGRAM. Even if the math is correct, missing diagram = -1 Mark.
Always define variables (Let 'E' be field, 'r' be distance) before starting math.

Master These & Secure 20+ Marks.

Prepared by Soumya Sir