Which American inventor introduced a hoe-shaped safety razor with a guard along one edge in 1880?

Which is a method of graphic tracing of the electric current generated by heart muscle during a heartbeat, first developed by Dutch physiologist Willem Einthoven in 1903?

Which was the first practical color photography process, introduced in France in 1907 by Auguste and Louis Lumière?

In 1900 who introduced the Brownie, a simple box camera with a removable film container?

In 1908 Swiss chemist Jacques E. Brandenberger designed a machine for continuous production of which strong transparent film?

In 1914 the world’s first two electric traffic lights were installed in which American city?

In 1923 which Russian-born American electronic engineer filed a patent for an all-electronic television system, which had cathode-ray tubes for both transmitting and receiving images?

Which American physicist created a one-step process for developing and printing photographs?

Which electrostatic dry-copying process, invented by Chester F. Carlson, was used to quickly create reproductions of documents?

Who invented the first contact lens, made of glass and developed to correct irregular astigmatism, in 1887?

In the 1940s Swiss engineer George de Mestral saw tiny hooks on the burrs clinging to his hunting jacket and invented the hook-and-loop fastener system known as what?

Which diagnostic imaging method uses a low-dose beam of X-rays that crosses the body in a single plane at many different angles?