Entry Test MCQ :: Atomic Spectra

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21.

When X-rays are passed through successive aluminum sheets what happens to their thickness?

A.	increases	B.	it decreases
C.	it remains same	D.	sometimes increases and sometimes decreases

22.

The penetrating power of X-rays is comparable with that of

A.	? - rays	B.	? - rays
C.	? - rays	D.	all of above

23.

Quality of X-rays depends upon ___________ A-filament current B-accelerating voltage C-material of the target

A.	A&B	B.	B&C
C.	A&C	D.	A B & C

24.

Radiation produced from TV picture tube is

A.	?-rays	B.	X-rays
C.	Far infrared.	D.	Infrared

25.

In an X-ray tube electrons each of charge e are accelerated through V potential difference allowed to hit a metal target. The wavelength of the X-rays emitted is

A.	he/ev	B.	he/Vc
C.	eV/h	D.	impossible to predict

26.

The minimum wavelength of X-rays can further be reduced by

A.	Reducing the pressure or cooling the target.	B.	Increasing the temperature of the filament.
C.	Using a target element of higher atomic number.	D.	Increasing the potential difference between the cathode and the target.

27.

The characteristic X-rays spectrum is due to

A.	The illumination of the target metal by ultra-violet radiation.	B.	The bombardment of the target by protons.
C.	The bombardment of target by electrons.	D.	The absorption of ? radiation by the target metal.

28.

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

29.

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.

30.

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