The Doppler effect
https://torrscientific.co.uk/wp-content/uploads/2025/08/TSL-The-Doppler-Effect-1.mp4...
Photons vs waves
https://torrscientific.co.uk/wp-content/uploads/2025/08/Photons-vs-waves.mp4...
How thin film coatings work
https://torrscientific.co.uk/wp-content/uploads/2025/08/How-thin-film-coatings-work.mp4...