Electromagnetic Waves and Visible Light
Electromagnetic waves are transverse waves that don't need any material to travel through - they can zip through empty space at an incredible 300,000,000 metres per second (the speed of light). Think of them as ripples of energy that can travel from the sun to Earth through the vacuum of space.
The electromagnetic spectrum follows a specific order from lowest to highest frequency: Radio, Microwave, Infrared, Visible Light, Ultraviolet, X-ray, Gamma. As frequency increases, wavelength gets shorter - it's like a see-saw relationship where one goes up as the other goes down.
Visible light - the only part we can actually see - has its own spectrum within the electromagnetic family. The colours go: Red, Orange, Yellow, Green, Blue, Indigo, Violet. Red light has the longest wavelength and lowest frequency, while violet has the shortest wavelength and highest frequency.
When EM waves interact with matter, they cause changes in atoms and their nuclei. Radio waves, for example, are created when electrons oscillate in electrical circuits (like in your phone's antenna), and they can also be absorbed by similar circuits.
Key Point: Remember the phrase "Richard Of York Gave Battle In Vain" to recall the visible light spectrum order!
However, some electromagnetic waves can be dangerous. Gamma rays and X-rays are ionising - they pack enough energy to knock electrons off atoms, potentially causing cell mutations that could lead to cancer or genetic defects. Even UV rays from sunlight can increase skin cancer risk and cause premature ageing if you're exposed to too much.
