Which pair is credited with inventing the tungsten lightbulb?

Which pair is credited with inventing the tungsten lightbulb?

• A. Thomas Edison and Joseph Swan
• B. Nikola Tesla and George Westinghouse
• C. Sandor Just and Franjo Hanaman
• D. James Clerk Maxwell and Albert Einstein

Answer: (C)

The key idea is identifying who first created a practical tungsten filament lamp. Tungsten is chosen for filaments because its very high melting point allows it to glow brightly and last longer than carbon filaments. To keep tungsten from evaporating at those high temperatures, bulbs must be evacuated or filled with an inert gas. Sandor Just and Franjo Hanaman are credited with inventing the tungsten lightbulb, having patented the first practical tungsten filament lamp in 1904. This milestone marked the transition from carbon filaments to tungsten, which underpins most modern incandescent lighting. The other names are associated with different developments: Edison and Swan worked on carbon-filament lamps, Tesla and Westinghouse with alternating current systems, and Maxwell and Einstein with foundational physics concepts. Those do not describe the initial tungsten filament invention.

The key idea is identifying who first created a practical tungsten filament lamp. Tungsten is chosen for filaments because its very high melting point allows it to glow brightly and last longer than carbon filaments. To keep tungsten from evaporating at those high temperatures, bulbs must be evacuated or filled with an inert gas.

Sandor Just and Franjo Hanaman are credited with inventing the tungsten lightbulb, having patented the first practical tungsten filament lamp in 1904. This milestone marked the transition from carbon filaments to tungsten, which underpins most modern incandescent lighting.

The other names are associated with different developments: Edison and Swan worked on carbon-filament lamps, Tesla and Westinghouse with alternating current systems, and Maxwell and Einstein with foundational physics concepts. Those do not describe the initial tungsten filament invention.