Q.What are EM waves?

[!TLDR] EM waves are transverse waves of oscillating electric and magnetic fields, produced by accelerated charges, that carry energy through space (including vacuum) without needing any material medium. [!ANSWER] Waves of mutually perpendicular, sinusoidally oscillating electric and magnetic fields, produced by accelerating charges, that propagate through space (even vacuum) at speed c.

As defined in section 13.2.1, EM waves are waves caused by the acceleration of charged particles, consisting of electric and magnetic fields vibrating sinusoidally at right angles both to each other and to the direction of propagation -- so they are transverse waves. They arise because an oscillating charge sets up an oscillating electric field, which produces an oscillating magnetic field, which regenerates the electric field, and so on, letting the disturbance propagate outward through space carrying energy with it, at the fixed vacuum speed $c\approx3\times10^8$ m/s (section 13.2.2), without requiring any material medium to travel through. [!ANSWER] Waves of mutually perpendicular, sinusoidally oscillating electric and magnetic fields, produced by accelerating charges, that propagate through space (even vacuum) at speed c.

State the formal definition from section 13.2.1, combining the source (accelerated charges), the structure (perpendicular oscillating E and B), and the key propagation property (speed c, no medium needed).

Giving only a partial definition, such as mentioning only that EM waves 'carry energy' without describing their actual structure (oscillating, perpendicular E and B fields).