31.
What invention is credited to the Russian born American inventor Vladimir Kosma Zworykin?

32.
Benjamin Franklin was a prolific inventor. He invented the lightning rod, the Franklin stove, studied electricity, discovered the Gulf Stream, started the first library, and on and on. Among his many other inventions, what musical instrument did he invent?

33.
What Thomas Davenport invented?

34.
What Elisha Otis invented?

35.
Where was the yo-yo invented?

36.
For what does the world owe Almon Strowger a debt of gratitude?

37.
In which decade was the telegraph invented?

38.
What inspired reflecting road lights to be invented?

39.
When were blue jeans invented?

40.
Who invented Electric Generator?