341. In optic fiber transmission the repeater are separated through a distance of __________ km in newer system?
A. 300km
B. 200km
C. 100km
D. 20km

342. Michelson devised the formula to calculate the speed of light_______________?
A. C = 4fd
B. C = 8fd
C. C = 16fd
D. C = 5/2fd

343. A convex lens acts as a diverging lens if the_________________?
A. object is beyond C
B. if the object is with in C
C. if the object is within f
D. both B and C

344. The equation θ = 1.22 λ/D was devised by_______________?
A. Newton
B. Einstein
C. Raleigh
D. Planks

345. Michelson calculated the speed of light using the instruments______________?
A. spectrometer
B. galvanometer
C. interferometer
D. none of these

346. Ratio of the weight of H-atom to that of an electron is approximately______________?
A. 18.336
B. 1836
C. 18360
D. 183.6

347. In hydrogen spectrum which one of the following series lies in the ultraviolet region ?
A. Balmer series
B. Pfund series
C. Bracket series
D. Lymann series

348. Excited atoms return to their ground state in_______________?
A. 10-10s
B. 10-8s
C. 10-6s
D. 10-9s

349. Hydrogen atom does not emit X-rays because _________________?
A. its energy levels are too close to each other
B. its energy levels are too far apart
C. it is too small in size
D. it has a single electron

350. X-ray are________________?
A. of unknown nature
B. high energy electrons
C. high energy photons
D. radio isotopes

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