Subjective test on Dual nature of Matter and Radiation & Nuclear Physics for CBSE Class XII sStudents

1. Date: 08.10.16
Sanjeet Singh
www.physicsgurukul.com
PHYSICS (Theory)
Time allowed: 1 hrs 30 min. Maximum Marks: 30
General Instructions:
(i) All questions are compulsory.
(ii) There are 15 questions in total.
(iii) Use of calculators are not permitted
(iv) There is no overall choice. However, internal choices have been provided in some of the
questions.
(iv) You may use the following values of physical constants wherever necessary:
8 -1
34
19
7 -1
0
9 2 -2
0
3 10 ms
6.626 10 Js
1.602 10 C
4 10 TmA
1
9 10 Nm C
4
c
h
e
 




 
 
 
 
 
1. (a) Draw a graph showing the variation of a pair of nucleons as a function of their separation. Indicate
the regions in which nuclear force is (i) Attractive (ii) repulsive.
(b) write two important conclusions which you can draw regarding the nature of nuclear forces.
(c) Write two characteristics features of nuclear force which distinguishes it from Coulomb force. 5
2. An electron, an alpha-particle and a proton have the same kinetic energy. Which one of these particles
has the largest de-Broglie wavelength? 2
3. Draw the logic symbol of ‘NOR’ gate. 1
4. In a plot of photoelectric current versus anode potential, how does
(i) the saturation current vary with anode potential for incident radiations of different frequencies
but same intensity?
(ii) the stopping potential vary for incident radiations of different intensities but same frequency?
(iii) photoelectric current vary for different intensities but same frequency of incident radiations?
Justify your answer in each case. 5

2. Date: 08.10.16
Sanjeet Singh
www.physicsgurukul.com
5. Two nuclei have mass number in the ratio 1:2. What is the ratio of their nuclear densities? 1
6. An electron is accelerated through a potential difference of 100 volts. What is the de-Broglie
wavelength associated with it? To which part of the electromagnetic spectrum does this value of
wavelength correspond? 2
7. plot graph showing the variation of stopping potential with the frequency of incident radiation for two
photosensitive materials having work functions W1 and W2 (W1 > W2). On what factor does the (i) slope
and (ii) intercept of the lines depend? 2
8. In the figure given below the input waveform is converted into the output waveform by a device ‘X’.
Name the device. 1
OR
What will be the values of the input A and B for the Boolean expression   . 1A B A B   ?
9. Name the physical quantity whose S.I. unit is JC-1
. Is it a scalar or a vector quantity? 1
10. Write Einstein’s photoelectric equation. State clearly the three salient features observed in
photoelectric effect, which can be explained on the basis of the above equation. 2
11. An electron and a photon each have a wavelength 1.00 nm. Find
(i) their momenta
(ii) the energy of the photon and
(iii) the kinetic energy of electron 3
12. Two nuclei have mass number in the ratio 1:8. What is the ratio of their nuclear radii? 1
13. Define the term ‘stopping potential’ in relation to photoelectric effect. 2
14. What happens to the width of depletion layer of a p-n junction when it is (i) forward biased, (ii)
reverse biased? 1
15. The stopping potential in an experiment on photoelectric effect is 1.5 V. What is the maximum kinetic
energy of the photoelectrons emitted? 1