This method is used to determine the velocity of ultrasonic waves using monochromatic sources like sodium vapour lamps.
2.
The electrical connections of high-pressure sodium vapour lamps, the yellow lamps for street lighting, are made of niobium alloyed with 1 % of zirconium.
3.
Consequently, high pressure sodium vapour lamps ( which are still yellowish, but closer to golden white ) are also used, at the cost of greater running expenses and increased light pollution.
4.
Meera Bagh is a posh colony, with well-carpeted internal roads, manicured parks and sodium vapour lamps lighting the internal roads at night, Guide Map . it is mainly maintained by RWA'A'Block with Mr . Samir Sethi Dussa as President, www . rwameerabagh . com
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