PPSC Physics Topic 7 Modern Physics With Answers

PPSC Physics Topic 7 Modern Physics

Sr. # Questions Answers Choice
1 The Compton effect in X-rays proves that Electrons have wave property x-rays have wave properly X-rays have particle characteristics Electrons cannot exist
2 X-rays spectrum may be Continuous spectrum Discontinuous spectrum Line spectrum Continuous and line spectrum
3 In which of the following studies x-rays are not helpful. Crystal structure Crystal surface Crystal symmetry Crystal atoms
4 Which of the following properties is not exhibited by X-rays. Interference Diffraction Polarization Deflection of electric field
5 A perfect back body Is a perfect absorber of all radiations Is a perfect reflector of all radiations Is a perfect reflector of visible lights radiations Is a brownish object
6 The maximum energy of emitted photoelectron is measured by the largest potential difference they can traverse The current they produce The potential difference they produce The speed with they emerge
7 The electrons behave as wave because. They can be diffracted by a crystal They can be defecting by magnetic field They can be deflecting by electric field they can produce ions in gases
8 In order to reduce uncertainty in momentum one must use light of. Short wavelength Large wavelength Wavelength of intermediate value Wavelength of any value
9 x-rays cannot produce Photoelectron Compton electron Electron positron pair All of these
10 Which of the following wavelength lies in X-rays region. 1 A 100 A 1,000 A 10,000 A
11 the wavelength of continuous X-rays is inversely proportional to. Intensity of incident electron beam Temperature of the target Intensity of X-rays The energy of electrons striking the target
12 What is the effect of electric and magnetic fields on X-rays X-rays are deflected X-rays are not deflected X-rays are sometimes deflected and sometimes not Nothing can be said
13 X-rays are not used in RADARs because They are not reflected by the target they are not completely absorbed by air They damage the target They are reflected by the target
14 On which factor cut off wavelength of X-rays coming from a Coolidge tube depends upon. Target material Accelerating voltage Filament temperature Separation between target and the filament
15 The X-rays coming from a X-rays tube Is monochromatic Has all wavelengths smaller than a certain maximum wavelength Has all wavelengths greater than a certain maximum wavelength has all wavelengths minimum than a certain maximum wavelength
16 The mass of an helium nucleus is equal to. 2.0015 u 3.0015 u 4.0015 u 5.0015 u
17 The maximum K.E of photo electrons depends upon Energy of incident radation Frequency of incident radiation Wavelength of incident radiation Mass of incident radiation
18 In annitilation of matter, positron and electron pair disappears into two Alpha particles Beta particles Game particles X-rays
19 The converse of pair production is Annihilation of matter Materialization Compton effect Photo electric effect
20 The process of pair production will take place if the energy of photon is greater than 0.21 MeV 0.51 MeV 1.51 MeV 1.21 MeV
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