## Tuesday, October 15, 2019

As CBSE Board Exams are near and expected to start from March 2020 onwards, so  Class 12 Board students start working extra hard to score high in Board Exams.Now a days students got very tensed about PHYSICS and try to search like -
• Important Topics for Class 12 Physics
• Most Important derivations in Class 12 Physics
• Important derivations on Electrostatics and Magnetism  etc.

Although All the Topics mentioned in CBSE Class 12 Physics Syllabus are Important ,and CBSE Board has changed the pattern of Question Paper and introduced Objective Type Questions of 20 marks which will check deep knowledge of student about the subject. So, students should work hard and go through CBSE Class 12 Sample Papers 2020 with Solution for understanding of pattern and level of Question Paper.
However All type of Questions has their own importance but the weightage of Derivations in CBSE Class 12 Physics Board Exam is high. So, after analysis of Previous Years Question Papers and Sample Papers issued by CBSE, we have prepared a complete list of Most Important derivations in Class 12 Physics,which we are going to provide you below :

## Most Important Derivations In CBSE Class 12 Physics

Unit – 1 Electrostatics

1. Derive Coulomb's law in vector form.
2. Derive an expression for electric field due to a short dipole (i) at a point on the axial line     (ii) at a point on equatorial line.
3. Derive an expression for Torque of electric dipole placed in uniform Electric Field.
4. Derive expression for Potential Energy of an electric dipole placed in uniform Electric Field.
5. Derive an expression for Electric field due to Infinitely long uniformly charged straight     wire.
6. Derive an expression for Electric field strength due to an infinite plane sheet of uniform  surface charge density.
7. Derive an expression for Electric field strength due to a uniformly charged thin spherical shell at external point, at the point on surface , at internal point.
8. Derive an expression for electric potential on (i) Axial Point (ii) Equatorial Point.
9. Derive expression for Capacitance of a Parallel plate Capacitor.
10. Derive expression for Energy stored in a charged capacitor.
11. Derive expression for the Capacitance of a parallel plate capacitor when a thin  dielectric slab is placed between the plates of capacitor.

Unit – 2 Current Electricity

12. Drive an expression for drift velocity of electron in a metallic wire placed in Electric field and also establish a relation between Electric current and  Drift velocity.
13. Derive expression for equivalent EMF of cells connected in series and parallel combinations.

Unit – 3 Magnetic Effects of Current and Magnetism

14. Derive expression for Magnetic field due to a Current carrying Circular coil at a point on its axis.
15. Derive expression for Magnetic field due to a Straight current carrying infinite length conductor.
16. Derive Magnetic field due to Current carrying Solenoid.
17. Derive expression for Force between two parallel current carrying conductors.

Unit – 4 Electromagnetic Induction and Alternating Current

18. Derive expression for Mutual Inductance between two current carrying coils.
19. Derive expressions for Mean and RMS value of Alternating current.
20. Derive expression for Impedance of a series RLC circuit.
21. Derive expression for Average power dissipation in series RLC circuit.

Unit – 5 Electromagnetic waves

22. What is Displacement Current and explain the Ampere – Maxwell Law.

Unit – 6 Optics

23. Show the formation of Image of a point object due to refraction of light by Spherical surface seperating two medium of refractive index n­1 and n2 and derive the relation between n1, n2, u, v and radius of curvature.
24. Derive Lens maker's formula.
25. Derive expression for Magnifying power of Compound microscope.
26. Derive an expression for Magnifying power of Astronomical Telescope.
27. Derive an expression for Angle of deviation and hence Prism formula.
28. Derive a mathematical expression for the width of Interference fringes obtained in Young's double slit experiment.
29. Explain the formation of a pattern of fringes obtained on the screen in Single slit Diffraction experiment and hence derive expression for width of Central Maxima.

Unit – 7 Dual Nature of Radiation and Matter

30. Derive Einstein's Photoelectric Equation.

Unit – 8 Atoms and Nuclie

31. Derive expression for Radius of Hydrogen Atom.
32. Derive expression for half life and mean life of a radioactive substance.

Unit – 9 Semiconductors and Electronic Devices

33. Derive Amplification factor for Common Base and Common Emitter Amplifiers.

Unit – 10 Communication systems

34. Derive an expression for covering range of TV transmission Tower.

Some Important Tips to score High in Class 12 Physics Exam

1. Understand the weightage of Chapters and plan your Study according to that:
• Electrostatics – 08 marks
• Current electricity – 07 marks
• Magnetic effect of current and magnetism – 08 marks
• EMI and AC – 08 marks
• EM Waves – 03 marks
• Optics – 14 marks
• Dual nature of radiation and matter – 04 marks
• Atoms and Nuclei – 06 marks
• Electronic Devices – 07 marks
• Communication systems – 05 marks
2. Underline or Highlight the Important Points and definitions for last time revision.

3. Draw neat and clean diagrams and graphs.

4. Try to practice Sample Papers with in time limit.

5. Practice at least last five years Question Papers.

Don't worry , work Hard ,Stay Happy !!

ALL THE BEST !!

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