Physics in Class 12 plays a vital role for students of the Bihar School Examination Board (BSEB) as it not only impacts board results but also serves as the foundation for entrance exams like JEE, NEET, and state-level competitive exams. A systematic understanding of formulas and key concepts is the most effective way to prepare.

In this post, you’ll find Bihar Board Class 12 Physics Formulas 2025-26 designed specially for Bihar Board Class 12 students (2025-26 session). This guide will help you revise quickly and improve your problem-solving skills.

Bihar Board Class 12 Physics Formulas 2025-26 and Short Notes – Chapter-wise Guide

Chapter 1: Electric Charges and Fields

Short Notes

• Electric charge can be positive or negative.

• Like charges repel, unlike charges attract.

• Coulomb’s law defines force between two point charges.

• Electric field is the region around a charge where force acts on another charge.

Important Formulas

• Coulomb’s Law:

  F=14πϵ0⋅q1q2r2F = \dfrac{1}{4\pi\epsilon_0} \cdot \dfrac{q_1 q_2}{r^2}F=4πϵ0​1​⋅r2q1​q2​​

• Electric Field due to Point Charge:

  E=14πϵ0⋅qr2E = \dfrac{1}{4\pi\epsilon_0} \cdot \dfrac{q}{r^2}E=4πϵ0​1​⋅r2q​

• Electric Dipole Moment:

  $$p=q\times 2a$$

• Torque on Dipole:

  $$\tau =pE\sin \theta$$

Chapter 2: Electrostatic Potential and Capacitance

Short Notes

• Electric potential is the work done in bringing a unit positive charge from infinity.

• Capacitance is the ability to store charge.

• Capacitors are used in circuits for energy storage.

Formulas

• Potential due to Point Charge:

  V=14πϵ0⋅qrV = \dfrac{1}{4\pi\epsilon_0} \cdot \dfrac{q}{r}V=4πϵ0​1​⋅rq​

• Electric Field and Potential Relation:

  E=−dVdrE = -\dfrac{dV}{dr}E=−drdV​

• Capacitance of Parallel Plate Capacitor:

  C=ϵ0AdC = \dfrac{\epsilon_0 A}{d}C=dϵ0​A​

• Energy Stored:

  U=12CV2U = \dfrac{1}{2} C V^2U=21​CV2

Chapter 3: Current Electricity

Short Notes

• Current is the flow of charges per unit time.

• Resistance opposes the flow of current.

• Ohm’s law gives relation between V, I, and R.

Formulas

• Ohm’s Law:

  $$V=IR$$

• Series Resistance:

  Req=R1+R2+R3R_{eq} = R_1 + R_2 + R_3Req​=R1​+R2​+R3​

• Parallel Resistance:

  1Req=1R1+1R2\dfrac{1}{R_{eq}} = \dfrac{1}{R_1} + \dfrac{1}{R_2}Req​1​=R1​1​+R2​1​

• Drift Velocity:

  vd=InAev_d = \dfrac{I}{nAe}vd​=nAeI​

Chapter 4: Moving Charges and Magnetism

Short Notes

• Moving charges produce a magnetic field.

• Right-hand thumb rule helps to find field direction.

• Force on a conductor in a magnetic field depends on current and orientation.

Formulas

• Force on Charge:

  $$F=qvB\sin \theta$$

• Force on Current Carrying Wire:

  $$F=BIL\sin \theta$$

• Torque on Coil:

  $$\tau =nBIA\sin \theta$$

• Field due to Long Wire:

  B=μ0I2πrB = \dfrac{\mu_0 I}{2\pi r}B=2πrμ0​I​

Chapter 5: Magnetism and Matter

Short Notes

• Earth behaves like a giant magnet.

• Magnetic dipole moment = strength × length.

• Magnetic field at axis and equator are different.

Formulas

• Dipole Moment:

  $$M=IA$$

• Field on Axis of Magnet:

  B=μ04π⋅2Mr3B = \dfrac{\mu_0}{4\pi} \cdot \dfrac{2M}{r^3}B=4πμ0​​⋅r32M​

• Field at Equator:

  B=μ04π⋅Mr3B = \dfrac{\mu_0}{4\pi} \cdot \dfrac{M}{r^3}B=4πμ0​​⋅r3M​

Chapter 6: Electromagnetic Induction

Short Notes

• Changing magnetic flux induces emf.

• Lenz’s law → Induced current always opposes cause.

• Self and mutual induction are key concepts.

Formulas

• Faraday’s Law:

  ε=−dΦdt\varepsilon = – \dfrac{d\Phi}{dt}ε=−dtdΦ​

• Self-Inductance:

  ε=−LdIdt\varepsilon = -L \dfrac{dI}{dt}ε=−LdtdI​

• Energy Stored:

  U=12LI2U = \dfrac{1}{2} L I^2U=21​LI2

Chapter 7: Alternating Current

Short Notes

• AC changes direction with time.

• RMS value is effective value of current/voltage.

• In resonance, impedance is minimum.

Formulas

• AC Voltage:

  V=V0sin⁡ωtV = V_0 \sin \omega tV=V0​sinωt

• RMS Value:

  Vrms=V02V_{rms} = \dfrac{V_0}{\sqrt{2}}Vrms​=2​V0​​

• Power:

  $$P=VI\cos \varphi$$

• Resonant Frequency:

  f=12πLCf = \dfrac{1}{2\pi \sqrt{LC}}f=2πLC​1​

Chapter 8: Electromagnetic Waves

Short Notes

• EM waves travel at speed of light.

• They are transverse in nature.

• Electric and magnetic fields are perpendicular.

Formulas

• Wave Speed:

  c=1μ0ϵ0c = \dfrac{1}{\sqrt{\mu_0 \epsilon_0}}c=μ0​ϵ0​​1​

• Field Relation:

  EB=c\dfrac{E}{B} = cBE​=c

Chapter 9: Ray Optics and Optical Instruments

Short Notes

• Reflection and refraction are basic principles.

• Lenses form images used in microscopes/telescopes.

• Total internal reflection is used in fiber optics.

Formulas

• Lens Formula:

  1f=1v−1u\dfrac{1}{f} = \dfrac{1}{v} – \dfrac{1}{u}f1​=v1​−u1​

• Magnification:

  M=vuM = \dfrac{v}{u}M=uv​

• Critical Angle:

  sin⁡C=1μ\sin C = \dfrac{1}{\mu}sinC=μ1​

Chapter 10: Wave Optics

Short Notes

• Light shows interference and diffraction.

• Young’s double slit proves wave nature of light.

• Polarisation proves transverse nature.

Formulas

• Path Difference:

  Δx=λDd\Delta x = \dfrac{\lambda D}{d}Δx=dλD​

• Fringe Width:

  β=λDd\beta = \dfrac{\lambda D}{d}β=dλD​

• Diffraction:

  $$a\sin \theta =n\lambda$$

Chapter 11: Dual Nature of Matter and Radiation

Short Notes

• Light has particle and wave dual nature.

• Einstein explained photoelectric effect.

• de Broglie proved matter waves.

Formulas

• Photoelectric Equation:

  hν=ϕ+12mv2h\nu = \phi + \dfrac{1}{2} m v^2hν=ϕ+21​mv2

• de Broglie Wavelength:

  λ=hmv\lambda = \dfrac{h}{mv}λ=mvh​

Chapter 12: Atoms and Nuclei

Short Notes

• Bohr’s model explains hydrogen spectrum.

• Nucleus is very small compared to atom.

• Nuclear energy comes from binding energy.

Formulas

• Radius of nth Orbit:

  rn=n2h2ϵ0πme2r_n = n^2 \dfrac{h^2 \epsilon_0}{\pi m e^2}rn​=n2πme2h2ϵ0​​

• Energy of nth Orbit:

  En=−13.6n2 eVE_n = – \dfrac{13.6}{n^2} \ eVEn​=−n213.6​ eV

• Mass-Energy Relation:

  E=mc2E = mc^2E=mc2

• Nuclear Radius:

  R=R0A1/3R = R_0 A^{1/3}R=R0​A1/3

Chapter 13: Semiconductor Electronics

Short Notes

• Semiconductors are used in diodes, transistors.

• Doping changes conductivity.

• p-n junction is the basis of modern electronics.

Formulas

• Conductivity:

  $$\sigma =nq\mu$$

• Resistance:

  R=ρlAR = \dfrac{\rho l}{A}R=Aρl​

• Diode Current:

  I=I0(eeVkT−1)I = I_0 \left(e^{\frac{eV}{kT}} – 1\right)I=I0​(ekTeV​−1)

  Bihar Board Class 12 Physics Formulas 2025-26

Conclusion

This blog provides chapter-wise Physics formulas with short notes for Bihar Board Class 12th students. By revising these formulas daily and understanding key points, you can score higher marks in board exams and also perform well in competitive exams.

 Tip: Make a formula chart and revise before exams to boost speed and accuracy.

FAQs 

Bihar Board Class 12 Physics Formulas 2025-26 and Short Notes

Q1. Why are Physics formulas important for Class 12 Bihar Board exams?

Answer: Formulas form the base of numerical problems. By memorizing and practicing them, students can solve questions faster and more accurately, which helps in scoring high marks.

Q2. How many chapters are there in Bihar Board Class 12 Physics?

Answer: There are 13 chapters in Bihar Board Class 12 Physics, covering topics like Electrostatics, Magnetism, Optics, Dual Nature, Atoms, Nuclei, and Electronics.

Q3. Which chapters in Class 12 Physics carry the highest weightage in board exams?

Answer: Usually, Electrostatics, Current Electricity, Optics, Atoms & Nuclei, and Semiconductor Electronics have higher weightage in Bihar Board exams.

Q4. How can I easily remember Physics formulas?

Answer: Make a formula notebook or chart, revise daily, and practice numerical problems regularly. Using short tricks and derivations also helps in better retention.

Q5. Are these formulas also useful for JEE and NEET exams?

Answer: Yes, most of these formulas are also part of JEE Main/Advanced and NEET syllabus. So, preparing them for Bihar Board will also strengthen competitive exam preparation.

Q6. What is the best strategy to prepare Physics for Bihar Board 2025 exams?

Answer:

1. Revise chapter-wise short notes.

2. Memorize all important formulas.

3. Solve previous year question papers.

4. Practice numerical questions daily.

Q7. Do I need to memorize derivations along with formulas?

Answer: Yes. In Bihar Board exams, derivations are frequently asked. Memorizing derivations also helps in understanding formulas better.

Q8. Which reference book should I use along with NCERT for Physics?

Answer: Apart from NCERT (Bihar Board prescribed book), you can use HC Verma (Concepts of Physics) and NCERT Exemplar for extra practice.

Q9. How much time should I give daily to revise Physics formulas?

Answer: At least 30 minutes daily should be dedicated to formula revision. Before exams, increase the revision time to 1 hour per day.

Q10. Can I download these formulas as PDF for revision?

Answer: Yes, these formulas can be made into a PDF format for easy download and daily revision. It helps students revise quickly without searching in textbooks.

Now the blog has:

Bihar Board Class 12 Physics Formulas 2025-26

• Intro

• Chapter-wise formulas

• Short notes (quick concepts)

• 10 FAQsSubscribe My Youtube channel