Modern Physics Formula for NEET 2026 Exam

Modern Physics formula sheet for NEET 2026: Chapter-wise

This formula sheet provides the most important NEET Modern Physics formulas for the chapters Dual Nature of Matter and Radiation, Atoms and Nuclei, and Electronic Devices. The formulas are easy to remember, chapter-wise, and cover most scoring concepts required for NEET. This comprehensive list of Modern Physics equations for NEET helps students quickly revise, practice important concepts, and improve their preparation efficiently. It is an effective tool for last-minute revision and concept reinforcement in Modern Physics.

Dual Nature of Matter and Radiation

The formulas with equations are given below:

1. This formula helps to find the wavelength of a moving particle using its mass and velocity:
   $\lambda ={\displaystyle \frac{h}{p}}={\displaystyle \frac{h}{mv}}$
   Example: If $v={10}^6$ m/s, $m=9.1\times {10}^{-31}$ kg, then
   $\lambda ={\displaystyle \frac{6.63\times {10}^{-34}}{9.1\times {10}^{-31}\times {10}^6}}=7.29\times {10}^{-10}$ m

2. This is the formula to calculate kinetic energy using wavelength:
   $KE={\displaystyle \frac{h^2}{2m{\lambda }^2}}$
   Example: For $\lambda =1\times {10}^{-10}$ m,
   $KE={\displaystyle \frac{(6.63\times {10}^{-34}{)}^2}{2\times 9.1\times {10}^{-31}\times (1\times {10}^{-10}{)}^2}}\approx 2.4\times {10}^{-18}$ J

3. This is Einstein's photoelectric equation showing the energy of the incident light:
   $h\nu =\varphi +{\displaystyle \frac{1}{2}}m{v}^2$
   Example: If $\varphi =2$ eV, and $h\nu =3$ eV,
   ${\displaystyle \frac{1}{2}}m{v}^2=3-2=1$ eV

4. This gives the relation between threshold frequency and work function:
   $\varphi =h{\nu }_0$
   Example: If ${\nu }_0=5\times {10}^{14}$ Hz,
   $\varphi =6.63\times {10}^{-34}\times 5\times {10}^{14}=3.315\times {10}^{-19}$ J

5. This relates to stopping potential and maximum kinetic energy:
   $e{V}_0={\displaystyle \frac{1}{2}}m{v}_{\text{max}}^2$
   Example: If $v_{\text{max}}={10}^6$ m/s, then
   $V_0={\displaystyle \frac{1}{2}}\times {\displaystyle \frac{9.1\times {10}^{-31}\times ({10}^6{)}^2}{1.6\times {10}^{-19}}}\approx 2.84$ V

6. This formula links frequency with wavelength and speed of light:
   $\nu ={\displaystyle \frac{c}{\lambda }}$
   Example: For $\lambda =500$ nm,
   $\nu ={\displaystyle \frac{3\times {10}^8}{500\times {10}^{-9}}}=6\times {10}^{14}$ Hz

7. This calculates the threshold frequency from the work function:
   ${\nu }_0={\displaystyle \frac{\varphi }{h}}$
   Example: If $\varphi =2$ eV,
   ${\nu }_0={\displaystyle \frac{2\times 1.6\times {10}^{-19}}{6.63\times {10}^{-34}}}\approx 4.83\times {10}^{14}$ Hz

8. This formula calculates the wavelength of an electron from the accelerating voltage:
   $\lambda ={\displaystyle \frac{h}{\sqrt{2meV}}}$
   Example: For $V=100$ V,
   $\lambda ={\displaystyle \frac{6.63\times {10}^{-34}}{\sqrt{2\times 9.1\times {10}^{-31}\times 1.6\times {10}^{-19}\times 100}}}\approx 1.23\times {10}^{-10}$ m

Atoms and Nuclei

1. This gives the radius of an atom’s orbit in Bohr’s model:
   $r_n={\displaystyle \frac{n^2{h}^2{ϵ}_0}{\pi m{e}^{2}Z}}=0.53,\text{AA}\cdot {\displaystyle \frac{n^2}{Z}}$
   Example: For hydrogen in 1st orbit ($n=1$),
   $r=0.53$ Å

2. This gives the energy of an electron in nth orbit:
   $E_n=-{\displaystyle \frac{13.6Z^2}{n^2}}$
   Example: For $Z=1$, $n=2$,
   $E=-{\displaystyle \frac{13.6}{4}}=-3.4$ eV

3. This gives the speed of an electron in nth orbit:
   $v_n={\displaystyle \frac{Z{e}^2}{2{ϵ}_{0}h}}\cdot {\displaystyle \frac{1}{n}}$
   Example: In hydrogen ($Z=1$, $n=1$),
   $v=2.18\times {10}^6$ m/s

4. This gives the wavelength of radiation emitted or absorbed:
   ${\displaystyle \frac{1}{\lambda }}=R{Z}^2({\displaystyle \frac{1}{n_1^2}}-{\displaystyle \frac{1}{n_2^2}})$
   Example: $n_2=3$, $n_1=2$, $Z=1$
   ${\displaystyle \frac{1}{\lambda }}=1.097\times {10}^7({\displaystyle \frac{1}{4}}-{\displaystyle \frac{1}{9}})=1.523\times {10}^6$ m⁻¹

5. This is the formula for binding energy using mass defect:
   $BE=\mathrm{\Delta }m\cdot c^2$
   Example: $\mathrm{\Delta }m=0.0025$ u
   $BE=0.0025\times 931=2.33$ MeV

6. This formula calculates the mass defect of a nucleus:
   $\mathrm{\Delta }m=Z{m}_p+(A-Z)m_n-M_{\text{nucleus}}$
   Example: For He-4:
   $\mathrm{\Delta }m=2(1.00728)+2(1.00867)-4.00260=0.0304$ u

7. This shows how the number of nuclei decays with time:
   $N=N_0{e}^{-\lambda t}$
   Example: If $\lambda =0.693$, $t=1$,
   $N=N_0{e}^{-0.693}={\displaystyle \frac{N_0}{2}}$

8. This formula gives the decay constant from the half-life:
   $\lambda ={\displaystyle \frac{0.693}{T_{1/2}}}$
   Example: For $T_{1/2}=10$ days,
   $\lambda =0.0693$ day⁻¹

9. This gives the activity of a radioactive sample:
   $A=\lambda N$
   Example: If $\lambda =0.1$, $N=500$,
   $A=50$ decays/s

Electronic Devices

1. This gives the current gain in a transistor:
   $\beta ={\displaystyle \frac{\mathrm{\Delta }{I}_C}{\mathrm{\Delta }{I}_B}}$
   Example: $I_C=3$ mA, $I_B=30$ μA
   $\beta ={\displaystyle \frac{3}{0.03}}=100$

2. This is the ratio of collector to emitter current:
   $\alpha ={\displaystyle \frac{\mathrm{\Delta }{I}_C}{\mathrm{\Delta }{I}_E}}$
   Example: $I_C=9$ mA, $I_E=10$ mA
   $\alpha =0.9$

3. These give the relation between alpha and beta in a transistor:
   $\beta ={\displaystyle \frac{\alpha }{1-\alpha }},\alpha ={\displaystyle \frac{\beta }{1+\beta }}$
   Example: If $\alpha =0.98$, then $\beta ={\displaystyle \frac{0.98}{0.02}}=49$

4. This gives the average current in full-wave rectifier:
   $I_{\text{avg(full wave)}}={\displaystyle \frac{2I_0}{\pi }}$
   Example: $I_0=10$ A,
   $I_{\text{avg}}={\displaystyle \frac{20}{\pi }}\approx 6.37$ A

5. This gives average current in half-wave rectifier:
   $I_{\text{avg(half wave)}}={\displaystyle \frac{I_0}{\pi }}$
   Example: $I_0=10$ A,
   $I_{\text{avg}}={\displaystyle \frac{10}{\pi }}\approx 3.18$ A

6. These are the efficiency values of rectifiers:
   ${\eta }_{\text{full wave}}=81.2$
   ${\eta }_{\text{half wave}}=40.6$

7. This shows Zener diode maintains constant voltage:
   $V_Z=\text{constant (in breakdown region)}$
   Example: If Zener breakdown at 5.6 V, output remains 5.6 V even if input rises.

8. These are the logic gate formulas:
   $Y_{\text{AND}}=A\cdot B$
   Example: $A=1$, $B=1$ → $Y=1$

9. The OR gate gives a high output (1) if at least one of the inputs is high:
   $Y_{\text{OR}}=A+B$
   Example: $A=1$, $B=0$ → $Y=1$

10. The NOT gate gives the inverse or complement of the input:
    $Y_{\text{NOT}}=\bar{A}$
    Example: $A=0$ → $Y=1$

11. The NAND gate gives a low output (0) only when all inputs are high:
    $Y_{\text{NAND}}=\overline{A\cdot B}$
    Example: $A=1$, $B=1$ → $Y=0$

12. The NOR gate gives a high output (1) only when all inputs are low:
    $Y_{\text{NOR}}=\overline{A+B}$
    Example: $A=0$, $B=0$ → $Y=1$

These formulas of Modern Physics for NEET have to be understood so that the students can do well in the exam. With practice and study, students can apply these formulas to solve Modern Physics questions without any difficulty. Smart revision strategy and practice of these equations from time to time will help the students have a clear idea about Modern physics and perform well in preparation for the NEET 2026 exam.

Importance of Modern Physics in NEET 2026

Modern physics talks about new concepts in physics that came after Newton’s time. It mainly deals with two big discoveries: relativity and quantum mechanics. These ideas help us understand things like the photoelectric effect, how atoms work (Bohr’s model), nuclear physics, and radioactivity.

Learning the important Modern Physics formulas for NEET 2026 is effective, as many questions are directly based on these formulas, and knowing them helps you solve problems quickly in the NEET exam.

Students who are wondering how to study Physics for NEET 2026 have to focus on Modern Physics topics for NEET, like the photoelectric effect, Rutherford's model of the atom, radioactivity, wave nature of matter, etc., as they are highly scoring and require less attention and practice, while preparing.

Chapter‑Wise Weightage of Modern Physics (2021-2025 Analysis)

The modern physics chapters for NEET 2026 focus on topics that came after Newton’s time and are important for the exam. These topics are formula‑driven, high‑yield, and together contribute 6-8 direct questions every year. The modern physics chapter-wise weightage analysis is given below: