On 13 December 1904, Hungarian Sándor Just and Croatian Franjo Hanaman were granted a Hungarian patent (No. 34541) for a tungsten filament lamp that lasted longer and gave brighter light than the carbon filament. Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1904. This type is often called Tungsram-bulbs in many European countries. Filling a bulb with an inert gas such as argon or nitrogen retards the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life. COUNT 5
QSN1 Which inventors patented the tungsten filament lamp? ANS1 Hungarian Sándor Just and Croatian Franjo Hanaman QSN2 When did Just and Hanaman receive their patent for the tungsten filament lamp? ANS2 13 December 1904 QSN3 Which company first marketed the tungsten filament lamp? ANS3 Tungsram QSN4 What type of gas fills a tungsten filament bulb? ANS4 argon or nitrogen QSN5 What is a common alternate name for the tungsten filament bulb in Europe? ANS5 Tungsram-bulbs