Q No 1: choose the correct option radiation emitted by target will be:
1. Which of the following series lies in ultraviolet region? A) Visible light B) Radio waves C) Ultraviolet D) X-rays
(a) Lyman (b) Balmer (c) Paschen (d) Pfund 21. The speed of electron in a box of size 10-14 m is 7.3 x 1010 m. We
2. Electric P.E of electron in the nth orbit of H-atom is infer that :
a) Electron does not reside in the box
b) Electron resides in the box
(a c) Electron cannot move with this speed.
3. Radiation with wavelength longer than red light is d) Both a and c
called 22. The stay time in normal exited state is:
(a) Ultraviolet (b) infrared (c) X-ray (d) visible radiation a) 1010s b) 10-10 s c) 10-8 s d) 10-3 s
4. Balmer series is obtained when all electronic 23. The wavelength of He-Ne Laser is:
transitions of hydrogen atoms terminate in a) 632.8mm b) 589nm c) 6328A0 d) 546 nm
(a) Ist orbit (b) 2nd orbit (c) 3rd orbit (d) none of these 24. The lasing material in He –Ne laser is:
5. The spectral series containing transitions terminating a) He b) Ne c) Argon d) Bromin
in the ground state of the hydrogen atom is called 25. Red light emitted from He-Ne Laser devise has wavelength
(a) Brackett series (b) Paschen series (a) 500nm (b) 632.8nm (c) 750nm (d) 550nm
(c) Balmer series (d) Lyman series 26. Period of metastable state is
6. An atom makes a transition from a state of energy E2 (a) 10-8 s (b) 10-5 s (c) 10-7 s (d) 10-3 s
to one of lower energy E1. Which of the followings 27. In helium –Neon laser % of Neon is
gives the wavelength of the radiation emitted? (a) 15% (b) 40% (c) 85% (d) 90%
hc hc c
28. The process in which there are less atoms in excited state as
E2 −E1 hc − compared to ground state is called?
(a) hc (b) E −E1 (c) E2 E1 (d) h ( E2 −E1 )
2 (a) Population inversion (b) normal population (c) can be both
7. The value of Rydberg's constant is (d) none
(a) 1.0974 x 10–7 m (b) 1.0974 x 107 m 29. A de-excitation of electron by stimulated emission
7 –1
(c) 1.0974 x 10 m (d) none of these produces______ photons.
8. The magnitude of ionization potential for H is (a) 1 (b) 2 (c) 3 (d) 0
a) -1.51 V (b) –3.40 V (c) 13.6 V (d) 13 V 30. The speed of electron in 1st Bohr’s orbit,
9. Transitions of electrons between the various shells can a) 2.19 x 105 m s-1 c) 2.19 x 107 m s-1
produce? 6
b) 2.19 x 10 m s -1
d) 3.0 x 108 m s-1
(a) Characteristics X-rays (b) continuous X-rays
(c) Both X-rays (d) Soft X-rays
10. K-series of characteristic X-rays are produced when
all the transitions of inner-shell electrons terminate Q#:2 Give short answers to the following questions.
on:: (i) What are the advantages of lasers over ordinary light?
(a) M-shell b) k-shell (c) N-shell (d) L-shell (ii) Is energy conserved when an atom emits a photon of light?
11. The reverse process of photo-electric effect is called:2 (iii) Explain why laser action could not be occurring without
(a) Compton effect (b) Pair production population inversion between atomic levels?
(c) X-rays production d) radioactivity (iv) What do we mean when we say that the atom is excited?
12. X-rays were discovered by: (v) Bohr’s theory o f hydrogen atom is based upon several
(a) Roentgen (b) de Broglie (c) Maxwell (d) Compton assumptions. Does any of this assumption contradict classical
13. X-rays can exhibit the phenomenon of: physics?
(a) Interference (b) Diffraction (c) Polarization (d)All above
14. The rest mass of X-rays photon is:
(a) Infinite (b) Zero (c) 9.1×10–31 kg (d) 1.67×10–27 kg
15. The velocity of X-rays is equal to:
(a) Electromagnetic waves (b) Longitudinal waves
(c) Mechanical waves (d) Matter waves.
16. Continuous X-Rays are produced by:
(a) Accelerating electrons (c) Decelerating electrons
(b) Both “A” and “B” (d) Inner shell transitions
17. Wavelength of characteristics X-ray depend upon:
A) Filament current C) Accelerating potential
B) Nature of metal D) Both “B” and “C”
18. Minimum wavelength of X-Rays depend upon:
A) Target material C) Accelerating Voltage
B) Filament current D) Intensity of incident electrons
19. X-Ray region lies between:
A) -rays and radio waves C) Cosmic rays and -rays
B) -rays and ultraviolet D) Visible and Infrared
20. If electron of 60 keV strike a heavy target. Then
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