111. In which decade were the first successful diode and triode vacuum tubes invented?
(a) 1800s (b) 1880s (c) 1890s (d) 1900s
Answer
Answer : (d)
Explanation
Explanation : In 1904, John Ambrose Fleming invented the first practical electron tube called the ‘Fleming Valve’, which is a diode rectifier. In 1906, Lee de Forest invented the audion later called the triode, which provided signal amplification.