IIT JAM PHYSICS 2026

🌟 ELECTROMAGNETISM – COMPLETE COMBINED TABLE (WITH FORMULAE & CONDITIONS)

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🔹 ELECTROSTATICS

Topic	Definition	Formulae	Conditions / Valid When	Limitations	Symbols Meaning
Coulomb’s Law	Force between two stationary point charges	$\vec F=\frac{1}{4\pi\varepsilon_0}\frac{q_1q_2}{r^2}\hat r$	Point charges, electrostatics, vacuum or uniform medium	Moving charges, relativistic speeds	$q$=charge, $r$=distance, $\varepsilon_0$=permittivity
Electric Field	Force per unit positive test charge	$\vec E=\frac{\vec F}{q}$	Test charge very small, static field	Large test charge	$E$=field strength
Electric Potential	Work done per unit charge	$V=\frac{W}{q}$	Conservative electrostatic field	Time-varying fields	$V$=potential
Relation $E$–$V$	Field as potential gradient	$\vec E=-\nabla V$	Electrostatics	Non-conservative fields	$\nabla$=gradient
Gauss’s Law	Electric flux equals enclosed charge	$\oint\vec E\cdot d\vec A=\frac{Q}{\varepsilon_0}$	Always true; useful for symmetry	Asymmetric charges	$Q$=charge
Boundary Conditions	Field behavior at interface	$E_{\perp}$, $D_{\perp}$, $E_{\parallel}$ continuity	Static fields	Time-varying fields	$\perp,\parallel$=normal, tangential
Laplace’s Equation	Potential in charge-free region	$\nabla^2 V=0$	No charge, electrostatics	Charge present	$\nabla^2$=Laplacian
Poisson’s Equation	Potential with charge	$\nabla^2 V=-\rho/\varepsilon_0$	Charge present	Charge-free region	$\rho$=charge density

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🔹 CONDUCTORS & DIELECTRICS

Topic	Definition	Formulae	Conditions	Limitations	Symbols
Conductor (ES)	Material allowing free charge motion	$E=0$ inside	Electrostatic equilibrium	Current flow	$E$=electric field
Capacitance	Charge per unit potential	$C=\frac{Q}{V}$	Linear dielectrics	Edge effects	$C$=capacitance
Parallel Plate Capacitor	Two plates storing charge	$C=\frac{\varepsilon A}{d}$	Uniform field	Fringing	$A,d$=area, gap
Dielectric Polarization	Dipole moment per volume	$\vec P=\chi_e\varepsilon_0\vec E$	Linear dielectrics	Strong fields	$\chi_e$=susceptibility
Bound Volume Charge	Charge due to polarization	$\rho_b=-\nabla\cdot\vec P$	Non-uniform polarization	Uniform $P$	$\rho_b$=bound charge
Bound Surface Charge	Surface polarization charge	$\sigma_b=\vec P\cdot\hat n$	Surface polarization	Zero normal $P$	$\hat n$=normal
Electrostatic Energy	Energy stored in field	$U=\frac{1}{2}CV^2$	Static fields	Time-varying fields	$U$=energy

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🔹 MAGNETOSTATICS

Topic	Definition	Formulae	Conditions	Limitations	Symbols
Biot–Savart Law	Field due to current element	$d\vec B=\frac{\mu_0}{4\pi}\frac{I d\vec l\times\hat r}{r^2}$	Steady current	Time-varying current	$\mu_0$=permeability
Ampere’s Law	Magnetic circulation	$\oint\vec B\cdot d\vec l=\mu_0I$	Symmetry, steady current	Time-varying fields	$I$=current
Lorentz Force	Force on moving charge	$\vec F=q(\vec E+\vec v\times\vec B)$	Classical speeds	Relativistic speeds	$\vec v$=velocity

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🔹 ELECTROMAGNETIC INDUCTION

Topic	Definition	Formulae	Conditions	Limitations	Symbols
Faraday’s Law	EMF due to flux change	$\mathcal{E}=-\frac{d\Phi_B}{dt}$	Changing flux	Constant flux	$\Phi_B$=flux
Self Inductance	EMF due to own current	$\mathcal{E}=-L\frac{dI}{dt}$	Fixed geometry	Saturation	$L$=inductance
Mutual Inductance	EMF due to nearby coil	$\mathcal{E}=-M\frac{dI}{dt}$	Fixed position	Variable spacing	$M$=mutual inductance

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🔹 AC & DC CIRCUITS

Topic	Definition	Formulae	Conditions	Limitations	Symbols
Ohm’s Law	Relation between V and I	$V=IR$	Linear conductor	High temperature	$R$=resistance
AC Voltage	Alternating source	$V=V_0\sin\omega t$	Sinusoidal	Non-sinusoidal	$\omega$=angular freq
Inductive Reactance	Opposition by inductor	$X_L=\omega L$	AC only	DC	$X_L$=reactance
Capacitive Reactance	Opposition by capacitor	$X_C=\frac{1}{\omega C}$	AC only	DC	$X_C$=reactance
Impedance (RLC)	Total opposition	$Z=\sqrt{R^2+(X_L-X_C)^2}$	Linear AC	Harmonics	$Z$=impedance

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🔹 MAXWELL & EM WAVES

Topic	Definition	Formulae	Conditions	Limitations	Symbols
Displacement Current	Current due to changing E	$I_d=\varepsilon_0\frac{d\Phi_E}{dt}$	Time-varying E	Static fields	$\Phi_E$=E flux
Maxwell’s Equations	Complete EM laws	$\nabla\cdot\vec E=\rho/\varepsilon_0$ etc.	Classical fields	Quantum scale	$\rho$=density
Plane EM Wave	Propagating EM disturbance	$c=\frac{1}{\sqrt{\mu_0\varepsilon_0}}$	Far-field	Near-field	$c$=speed
Poynting Vector	Energy flow density	$\vec S=\frac{1}{\mu_0}\vec E\times\vec B$	Radiation fields	Near-field	$S$=power/area
EM Energy Density	Energy per volume	$u=\frac{1}{2}(\varepsilon_0E^2+\frac{B^2}{\mu_0})$	Linear media	Nonlinear media	$u$=energy density

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🔹 REFLECTION & REFRACTION (NORMAL INCIDENCE)

Topic	Formulae	Conditions	Limitations
Reflection Coefficient	$R=\left(\frac{n_1-n_2}{n_1+n_2}\right)^2$	Normal incidence	Oblique incidence
Transmission Coefficient	$T=\frac{4n_1n_2}{(n_1+n_2)^2}$	Lossless dielectric	Conducting media

 

Topic	Definition	Formulae	Conditions	Limitations	Symbols
Biot–Savart Law	Field due to current element	( d\vec B=\frac{\mu_0}{4\pi}\frac{I d\vec l\times\hat r}{r^2} )	Steady current	Time-varying current	(\mu_0)=permeability
Ampere’s Law	Magnetic circulation	( \oint\vec B\cdot d\vec l=\mu_0I )	Symmetry, steady current	Time-varying fields	(I)=current
Lorentz Force	Force on moving charge	( \vec F=q(\vec E+\vec v\times\vec B) )	Classical speeds	Relativistic speeds	(\vec v)=velocity