CCPY 2025.02.25 Some useful websites:

(1) 
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

(2) Simulations
https://phet.colorado.edu/en/simulations/filter?subjects=physics&type=html

https://phet.colorado.edu/sims/html/molecules-and-light/latest/molecules-and-light_all.html

https://phet.colorado.edu/sims/cheerpj/photoelectric/latest/photoelectric.html?simulation=photoelectric

https://phet.colorado.edu/en/simulations/blackbody-spectrum