311. The minimum wavelength of X-rays produced by the bombardment of electrons on the screen of a television set where the accelerating potential is 2.0K V will be______________?
A. 6.2 x 10-10m
B. 9.1 x 10-18m
C. 3.11 x 10-10m
D. 4 x 10-10m

312. Maximum frequency in the spectrum from X-ray tube is directly proportional to the______________?
A. Number of incident electron i.e. filament current
B. The kinetic energy of the incident electron i.e. the potential difference through which they are accelerated
C. The soft target which can easily emit electrons
D. All of above are correct

313. X-rays are diffracted by a crystal but not by a diffraction grating because_____________?
A. The ions in a crystal are well arranged
B. The lines in a diffraction grating cannot reflect X-rays.
C. The penetration power of X-rays is high in a diffraction grating
D. The wavelengths of X-rays are of the same order of magnitude as the separation between atoms in a crystal

314. UV radiation can be produced by______________?
A. Heating the filament
B. Electron excitation in the gas
C. Ionization of atoms
D. All the above

315. Wave-like characteristic of electron is demonstrated by______________?
A. Line spectrum of atoms
B. Production of x-rays.
C. Diffraction by crystalline solids
D. Photoelectric effect

316. Electron cannot exist in the nucleus it is confirmed by observing that______________?
A. It does emit radiation
B. Its size as compare to proton and neutron is very small
C. No antiparticle of electron is present
D. The velocity of electron must be very high according to uncertainty principle

317. In normal state of energy the incident high energy photons will be______________?
A. Stimulated
B. Absorbed
C. Cause X-ray emission
D. Cause laser production

318. In laser production the state in which more atoms are in the upper state than in the lower one is called_____________?
A. Metal stable state
B. Normal state
C. Inverted population
D. All the above

319. The metastable state for an atom in laser light is_____________?
A. 10-4 sec
B. 10-5 sec
C. 10-3 sec
D. 10-8 sec

320. In He-Ne laser the lasing action is produced by_______________?
A. Ne only
B. He-Ne both
C. Electrons of He
D. Electrons Ne