Important Inventions and Discoveries in World » Exercise – 1
81. In which decade were the first successful diode and triode vacuum tubes invented?
(a) 1800s
(b) 1880s
(c) 1890s
(d) 1900s
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| Exam Name : UPSC, SSC, KVS, NVS, IBPS, RBI, SBI, RRB |
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