CLASS - XII PHYSICS
(Unit –Solid Dual nature of matter and radiation, Atom and Nuclei)
1
Calculate the energy associated in eV with a photon of wavelength 4000A o?
[1]
2
Mention one physical process for the release of electron from the surface of a metal?
[1]
3
Calculate the threshold frequency of photon for photoelectric emission from a metal of work
function 0.1eV?
[1]
Electron and proton are moving with same speed. Which will have more wavelength?
[1]
4
5
[1]
6
It is difficult to remove a free electron from copper than from sodium. Why?
[2]
7
Define photoelectric work function? What is its unit?
[2]
8
An electron and an alpha particle have the same debroglie wavelength associated with them?
How are their kinetic energies related to each other?
[2]
9
How many 𝛼 and 𝛽 particles are emitted when
90232
𝑇ℎ
changes to
82208
𝑃𝑏
[2]
10
[2]
11
12
13
14
Define threshold wavelength for photoelectric effect? Debroglie wavelength associated with
an electron associated through a potential difference V is 𝜆? What will be the new wavelength
when the accelerating potential is increased to 4V?
[3]
An electron has kinetic energy equal to 100eV. Calculate (1) momentum (2) speed (3)
Debroglie wavelength of the electron.
[3]
Photoelectric work function of a metal is 1eV. Light of wavelength 3000A o falls on it. What is
the velocity of the effected photoelectron?
[3]
The wavelength 𝜆 of a photon and debroglie wavelength of an electron have the same value.
Show that the energy of the photon is
15
2𝜆𝑚𝑐
ℎ
times the kinetic energy of electron where m, c
and h have their usual meanings.
[3]
Draw a graph showing the variation of stopping potential with frequency of the incident
radiations. What does the slope of the line with the frequency axis indicate. Hence define
[3]
threshold frequency?
16
The total energy of an electron in the first excited state of hydrogen atom is -34.eV. Calculate
(1) K.E of the electron in this state
(2) P.E of the electron in this state and
(3) Which of the answer would change of the choice. Justify your answer?
[3]
17
Prove that the speed of electron in the ground state of hydrogen atom is equal to the speed
of electron in the first excited state of hydrogen like Li ++ atom.
[3]
18
Draw a graph showing variation of potential energy of a pair of nucleon as a function of their
separation. Indicate the region in which the nuclear force is (a) Attractive (b) Repulsive.
Also write two characteristics features which distinguish it from the Coulomb’s force.
[3]
19
[3]
20
[3]
21
[3]
22
[3]
23
Muthuswami a resident of Kudankulam was all set to leave everything and shift to another
place in view of the decision of Government to start nuclear thermal power plant at
Kudankulam. His granddaughter Prachi, a science student, was really upset on the ignorant
decision of her grandfather. She could finall convince him not to shift, since adequate safety
measures to avoid any nuclear mishap have already been taken by the Government before
starting nuclear thermal plants.



What is the value displayed by Prachi in convincing her grandfather
What is the principle behind working of nuclear reactor
What are the main components of nuclear reactor.
[4]