Physics is one of the most scoring subjects in the Bihar School Examination Board (BSEB) Class 12 curriculum—especially when students master the formulas and understand their applications. Every numerical question in the exam is based on one or more key formulas from the NCERT and BSEB prescribed textbooks. To help students prepare effectively, this detailed guide covers Bihar Board Class 12 Physics formulas for all chapters along with solved examples.

Whether you are preparing for board exams, competitive tests, or revision, this complete chapter-wise collection will boost your confidence and help you score higher.

Bihar Board Class 12 Physics Formulas | Chapter-Wise List with Examples (2025 Guide)

Chapter-Wise Bihar Board Class 12 Physics Formulas with Examples

Chapter 1: Electric Charges and Fields

Important Formulas

1. Coulomb’s Law:

   F = k \frac{q_1 q_2}{r^2}

2. Electric Field:

   E = \frac{F}{q} = k \frac{Q}{r^2}

3. Electric Flux:

   \phi = E A \cos\theta

4. Gauss Law:

   \phi = \frac{Q_{enclosed}}{\epsilon_0}

Example

Two charges and are placed 1 m apart.

F = 9 \times 10^9 \cdot \frac{(2 \times 10^{-6})(3 \times 10^{-6})}{1^2} = 54 \, N

Chapter 2: Electrostatic Potential and Capacitance

Important Formulas

1. Potential due to point charge:

   V = k \frac{Q}{r}

2. Capacitance of a Parallel Plate Capacitor:

   C = \frac{\epsilon_0 A}{d}

3. Energy stored in capacitor:

   U = \frac{1}{2} C V^2

Example

A capacitor has and .

U = \frac{1}{2} \times 4 \times 10^{-6} \times 100^2 = 0.02 J

Chapter 3: Current Electricity

Important Formulas

1. Ohm’s Law:

   V = IR

2. Resistivity:

   R = \rho \frac{l}{A}

3. Power:

   P = VI = I^2 R = \frac{V^2}{R}

4. Series & Parallel Resistance:
   Series:

   R_{s} = R_1 + R_2 + \dots

   \frac{1}{R_{p}} = \frac{1}{R_1} + \frac{1}{R_2}

Example

If and ,

I = \frac{12}{6} = 2A

Chapter 4: Moving Charges and Magnetism

Important Formulas

1. Magnetic Force on Charge:

   F = qvB\sin\theta

2. Force on Current-Carrying Wire:

   F = B I L \sin\theta

3. Biot–Savart Law:

   B = \frac{\mu_0}{4\pi} \frac{I dl \sin\theta}{r^2}

Example

A wire of 2 m carries 5 A in a 0.2 T field:

F = 0.2 \times 5 \times 2 = 2N

Chapter 5: Magnetism and Matter

Important Formulas

1. Magnetic Dipole Moment:

   M = N I A

2. Magnetic Susceptibility:

   \chi = \frac{M}{H}

3. Torque on Magnetic Dipole:

   \tau = MB\sin\theta

Example

A 100-turn coil with area carries 2 A.

M = N I A = 100 \times 2 \times 0.05 = 10 Am^2

Chapter 6: Electromagnetic Induction

Important Formulas

1. Faraday’s Law:

   e = -\frac{d\phi}{dt}

2. Induced EMF in a rod:

   e = B l v

3. Self-Inductance:

   e = -L \frac{di}{dt}

Example

If flux changes by in 0.1 sec:

e = \frac{0.5}{0.1} = 5V

Chapter 7: Alternating Current

Important Formulas

1. AC Voltage:

   V = V_0 \sin\omega t

2. RMS Value:

   V_{rms} = \frac{V_0}{\sqrt{2}}

3. Impedance (LCR Circuit):

   Z = \sqrt{R^2 + (X_L - X_C)^2}

4. Reactances:

   X_L = \omega L,\quad X_C = \frac{1}{\omega C}

Example

If :

V_{rms} = \frac{100}{\sqrt{2}} = 70.7V

Chapter 8: Electromagnetic Waves

Important Formulas

1. Speed of EM wave:

   c = \frac{1}{\sqrt{\mu_0 \epsilon_0}}

2. Relationship:

   c = f\lambda

Example

If and :

c = f\lambda = 3 \times 10^8 m/s

Chapter 9: Ray Optics & Optical Instruments

Important Formulas

1. Mirror Formula:

   \frac{1}{f} = \frac{1}{v} + \frac{1}{u}

2. Magnification:

   m = \frac{h'}{h} = -\frac{v}{u}

3. Lens Formula:

   \frac{1}{f} = \frac{1}{v} - \frac{1}{u}

Example

A concave mirror forms an image at 30 cm, object at 60 cm:

\frac{1}{f} = \frac{1}{30} + \frac{1}{60} = \frac{1}{20}  
\Rightarrow f = 20cm

Chapter 10: Wave Optics

Important Formulas

1. Young’s Fringe Width:

   \beta = \frac{\lambda D}{d}

2. Angular Width of Central Maxima:

   \theta = \frac{\lambda}{a}

3. Path Difference:

   \Delta x = n\lambda

Example

\beta = \frac{6000 \times 10^{-10} \times 1}{0.03} = 2mm

Chapter 11: Dual Nature of Radiation and Matter

Important Formulas

1. Einstein Photoelectric Equation:

   h\nu = h\nu_0 + eV_s

2. De-Broglie Wavelength:

   \lambda = \frac{h}{mv}

Example

Electron moving at :

\lambda = \frac{6.63 \times 10^{-34}}{9.1 \times 10^{-31} \times 2 \times 10^6} 
= 3.63 \times 10^{-10} m

Chapter 12: Atoms

Important Formulas

1. Bohr Radius:

   r_n = n^2 a_0

2. Energy of Electron:

   E_n = -\frac{13.6}{n^2} eV

Example

Energy of electron in 2nd orbit:

E_2 = -\frac{13.6}{4} = -3.4 eV

Chapter 13: Nuclei

Important Formulas

1. Mass Defect:

   \Delta m = Z m_p + N m_n - m_{nucleus}

2. Binding Energy:

   E_B = \Delta m c^2

Example

If :
E_B = 0.01 \times 931 = 9.31 MeV

Chapter 14: Semiconductor Electronics

Important Formulas

1. Diode Equation:

   I = I_0 \left( e^{\frac{V}{nV_T}} - 1 \right)

2. Zener Breakdown Voltage:

   V_Z = constant

3. Current Gain (Transistor):

   \beta = \frac{I_C}{I_B}

Example

If and :

\beta = 50

Chapter 15: Communication Systems

Important Formulas

1. Modulation Index (AM):

   m = \frac{A_{max}-A_{min}}{A_{max}+A_{min}}

2. Bandwidth:

   BW = f_{max} - f_{min}

Example

AM signal:

m = \frac{10-2}{10+2} = \frac{8}{12} = 0.66

Conclusion

This complete chapter-wise list of Bihar Board Class 12 Physics formulas helps you revise all important concepts in one place. With formulas and examples included for every chapter, this guide is extremely useful for last-minute revision, board exam preparation, and competitive exam practice.

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FAQs – Bihar Board Class 12 Physics Formulas

1. What are the most important chapters for Bihar Board Class 12 Physics formulas?

All chapters are important, but students should focus more on Electrostatics, Current Electricity, Magnetism, Ray Optics, Wave Optics, and Semiconductor Electronics, as most numerical questions in the Bihar Board exam come from these sections.

2. Where can I get all Bihar Board Class 12 Physics formulas chapter-wise?

You can find a complete chapter-wise list of Bihar Board Class 12 Physics formulas in this article, covering all 15 chapters with important formulas and solved examples for easy revision and exam preparation.

3. Are the formulas the same for NCERT and Bihar Board Class 12 Physics?

Yes. Bihar Board follows the NCERT physics curriculum, so the formulas used in NCERT Class 12 Physics are the same formulas used in the Bihar Board Class 12 exam.

4. How can I memorize Class 12 Physics formulas effectively?

Use strategies like daily revision, writing formulas repeatedly, practicing numerical problems, and making chapter-wise formula charts. Solving past year papers also helps in remembering formulas better.

5. Are examples important along with formulas for the Bihar Board Physics exam?

Yes. Learning formulas alone is not enough—understanding their application through examples is crucial. The Bihar Board exam includes numerical questions that require accurate formula usage.

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