XII BSEK ( Karachi Board)
Note:- For 17.1, 17.2, 17.3, 17.4, 17.5, 17.6, 17.7 ,17.12 see theory
notes
Q.17.8 Why Compton
Ans. In Compton effect ,x rays of
wave length =1 Ao equivalent to energy=140 ev , were directed on the
graphite block, where binding energies of bounded electrons are =100 ev .If
visible light is used it possesses low frequency and these photons have
energies =0.1 ev, this energy is too small to be given to loosely bound
electrons to get them scattered.
Q.17.9 What phenomenon……………..related quantitatively?
Evidences
for wave Phenomenon
|
Evidences
for matter phenomenon
|
Interference of light
|
Black body radiation
|
Diffraction of light
|
Photo electric effect
|
Polarization of light
|
Compton effect
|
Optical Doppler’s effect
|
x ray production
|
Prod. Of electromagnetic waves
|
Ans.
Q.17.10 In what way the ……. and
protons?
Ans.
Characteristics
of particles of matter
|
Characteristics
of light (photons)
|
1.Non zero rest mass
|
1.Zero rest mass
|
2. They possess inertia
|
2.They consists of energy packets
|
3. Speed is always less than speed of light
|
3. They travel with the speed of light
|
4. They may be charged or uncharged
|
4. They are always neutral
|
5.They are guided by matter waves
|
5. No relation with the matter waves
|
6.E=1/2 mv2
|
6. E= hν
|
Q.17.11 In the photo electric effect the energy……..Explain.
Ans. When radiation strikes a
metal surface, it deposits its entire energy on some electron in the absorbing
surface>if energy of the photon (E= hν) exceeds the energy expend by the electron
in work against the force binding it to the surface (φ) it will emitted with
some energy. K.e < hν
Q.17.13 with the help of ………. Of an atom.
Ans. A/c to de broglie
hypothesis, an electron moving around nucleus is pictured as a kind of wave
packet. An electron can circle a nucleus indefinitely without radiating energy
provided that its orbit contains an integral number of de broglie wavelength.
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