The Genius of Britain Season 1 Episode 3 (The Genius of Britain s01e03) with title “The Human Zoo: How We Came to Understand the World” airs on Tuesday, June 1st 2010 at 09:00 pm via Channel 4.
Here is summary for The Genius of Britain Season 1 Episode 3 :

James Dyson tries to examines the lives of Michael Faraday, who provided energy at the flick of a switch, and Isambard Kingdom Brunel, the engineer responsible for the construction of trains and steam-powered ships.

Few hours after original series aired on TV, online streaming video for The Genius of Britain Season 1 Episode 3 usually available on Net and of course, if video available, as soon as possible will show you where you can watch this episode for free.