Intensity Of Electromagnetic Wave — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Intensity of Electromagnetic Wave Applicable to electromagnetic waves traveling in vacuum or air where the refractive index is approximately unity. Energy in a cylindrical volume of cross-section A and length c dt is calculated Total energy dU = u avg A c dt Intensity I is defined as dU / (A dt) Substituting dU gives I = u avg c Wave must be a plane wave Medium must be non-dispersive and non-absorbing Confusing average energy density with peak energy density Forgetting that u avg includes both electric and magnetic field components