can anyone give me the answer that
how Einstein derive the speed of light c.?

Question

can anyone give me the answer that
how Einstein derive the speed of light c.?

anonymous · Answer

Einstein did not derive the speed of light.  That was done by James Clerk Maxwell, who had worked very closely with Michael Faraday on the Electro-Magnetism concepts.  Both men are my two favorite Physicists, I strongly recommend a personal study of them, and EM.

anonymous · Answer

So Einstein only gave the Relativity theory

anonymous · Answer

Einstein did a great number of things in 1905, his "miracle year"; including writing the paper that won him the Nobel Prize and dealt with his work on the "photo-electric effect" .  He is most commonly known for Special and General Relativity though.  Search, "Einstein's Miracle Year" to learn more.