Electromagnetic Waves Mind Map

Displacement current is the effective current associated with a time-varying electric flux. It is given by I_d = epsilon_0 dPhi_E/dt and is introduced in Ampere's law to account for changing electric fields.

In answers, clearly distinguish conduction current I from displacement current I_d and mention that Maxwell's correction makes Ampere's law valid for time-varying electric fields.

An electromagnetic wave is a transverse wave made of oscillating electric and magnetic fields that are perpendicular to each other and also perpendicular to the direction of wave propagation.

For diagram questions, show three perpendicular directions and label the electric field, magnetic field, and propagation direction clearly.

The speed of electromagnetic waves in vacuum is c = 1/sqrt(mu_0 epsilon_0), approximately 3.0 x 10^8 m s^-1. Electromagnetic waves carry energy and momentum through their electric and magnetic fields.

In numerical answers, write units at every substitution step, especially for c, energy density, and momentum. This prevents mixing electric and magnetic field terms incorrectly.

The electromagnetic spectrum is the continuous range of electromagnetic radiations arranged according to frequency or wavelength, from radio waves at long wavelengths to gamma rays at very short wavelengths.

Memorise the spectrum in order and pair each region with one standard use and one key property. Also remember that frequency and wavelength vary inversely for waves in vacuum.