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In the 1920s,the development of practical radio communication was furthered by
Heat Pumps
Devices that transfer heat energy from a source to a destination, often used for heating and cooling buildings.
Fuel-Cell Cars
Vehicles that generate their power from a fuel cell, which produces electricity through a chemical reaction between hydrogen and oxygen, emitting only water.
Combustion Engine
An engine that generates mechanical power by burning a fuel-air mixture to create an explosive reaction.
Hydrogen
A chemical element with the symbol H and atomic number 1, known as the lightest element in the universe and a primary component in water molecules.
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