What are electromagnetic waves? How are they produced? Write four of their characteristics and draw a labelled diagram showing their transverse nature.

1. 1 · Define. EM waves are oscillating electric and magnetic fields, perpendicular to each other, travelling through space.
2. 2 · Production. An accelerated (oscillating) charge produces changing E and B fields that sustain each other; the wave has the frequency of the oscillating charge.
3. 3 · Characteristics.
   • No medium needed; speed c = 1/√(μ₀ε₀) in vacuum.
   • E₀/B₀ = c; E and B are in phase.
   • They carry energy from place to place.
   • They are not deflected by electric or magnetic fields.
4. 4 · Draw the wave. [Axes x, y, z; E sine curve in the x-z plane; B sine curve in the y-z plane; propagation along z; λ marked]
5. 5 · Real life. Sunlight and DTH signals are EM waves crossing empty space.
6. 6 · Close in one line. So, EM waves are transverse waves that need no medium.

Scoring tip: In the diagram, draw E and B with their peaks at the same points: they are in phase.