Download Physics Time: 3 Hours Max. Marks: 70

Sample Paper – 2011
Class – XII
Subject –Physics
Time: 3 Hours
Max. Marks: 70
General Instructions:
(i) All questions are compulsory.
(ii) Question numbers 1 to8 are very short answer type questions, carrying one mark
each,
(iii) Question numbers 9-18 are short answer type question, carry two marks each.
(iv) Question numbers 19to27 are also short answer type question, carrying 3 mark
each.
(v) Question number 28to30 are long answer type question carrying five marks each.
(vi) Use log tables for necessary calculations.
Question 1. What is the work done in moving a charge of 10 nC between two points on
an equipotent surface? (1 mark)
Question 2. Name the device used for measuring the internal resistance of a secondary
cell? (1 mark)
Question 3. What is the nature of magnetic field in a moving coil galvanometer? (1 mark)
a
Question 4. If a rate of change of current of 2 A/s induces an e.m.f.of 10mV in a
solenoid, what is the self -inductance of the solenoid? (1 mark)
Question 5. What type of magnetic material is used in making permanent magnets? (1
mark)
Question 6. Two metals A, B have work-functions 2eV, 4eV respectively. Which metal
has lower threshold wavelength for photoelectric effect? (1 mark)
Question 7. Which part of the electromagnetic spectrum is used in operating RADAR? (1
mark)
Question 8. Which type of biasing gives a semiconductor diode very high resistance? (1
mark)
Question 9. An electric dipole, when held at 300 with respect to a uniform electric field
of 104N/C, experiences a torque of 9 x 10-26Nm. Calculate the dipole moment of the
dipole. (2 marks)
Question 10. A set of n identical resistors, each of resistance R ohm, when connected in
series have an effective resistance X ohm and when the resistors are connected in
parallel, their effective resistance is Y ohm. Find the relation between R, X and Y. (2
marks)
Question 11. State Kirchhoff's rules for electrical networks. (2 marks)
Question 12. Show that Lenz's law is in accordance with the law of conservation of
energy. (2 marks)
Question 13. Draw a labeled diagram of Hertz's experiment for producing
electromagnetic waves. (2 marks)
Question 14. Give two differences between fringes formed in single slit diffraction and
Young's double slit experiment. (2 marks)
Question 15. Light of wavelength 600nm is incident on an aperture of size 2mm.
Calculate the distance up to which the ray of light can travel such that its spread is less
than the size of the aperture. (2 marks)
Question 16. Explain the principle used in Bunsen's grease photometer to compare the
illuminating powers of two light sources. (2 marks)
Question 17. A ray of light while traveling from a denser to a rarer medium undergoes
total internal reflection. Derive the expression for the critical angle in terms of the speed
of light in the respective media. (2 marks)
Question 18. Draw a graph showing the variation of binding energy per nucleon with
mass number of different nuclei. Mark the region where the nuclei are most stable. (2
marks)
Question 19. Name the logic gate shown in the diagram and give its truth table. (2 marks)
Question 20. State and explain Seebeck effect. (2 marks)
Question 21. Explain with the help of a circuit diagram how the value of an unknown
resistance can be determined using a Wheatstone bridge. Give the formula used. (3
marks)
Question 22. Earth receives an amount of heat radiation 1.4 x 103 W/m2 from the sun.
Assume that earth re-emits all the radiation received from the sun. Calculate the surface
temperature of the earth. (3 marks)
Question 23. A straight wire carries a current of 3A.Calulate the magnitude of the
magnetic field at a point 10cm away from the wire. Draw diagram to show the direction
of the magnetic field. (3 marks)
Question 24. Explain how a vibration magnetometer can be used to determine the
magnetic moment of a bar magnet. (3 marks)
Question 25. Deduce lens maker's formula for a thin biconvex lens. (3 marks)
Question 26. Explain the origin of spectral lines of hydrogen using Bohr's theory. (3
marks)
Question 27. A beam of electrons passes unelected through mutually perpendicular
electric and magnetic fields E and B respectively. If the electric field is cut-off ,the
electron beam moves in a circular path of radius 'r'.Derive the expression for e/m of
electrons in terms of r,E and B. (3 marks)
Question 28. Draw a labeled diagram of Van de Graff generator. Give its principle and
explain its working. (5 marks)
Question 29. Prove that the power dissipated in an ideal resistor connected to an a.c.
source is V2eff/R.Acapacitor,a resistor and a 40 mH inductor are connected in series to
an a.c. source of frequency 60 Hz. Calculate the capacitance of the capacitor, if the
current is in phase with the voltage. (2+3 marks)
Question 30. Explain with the help of a circuit diagram the working principle of a
transistor as an amplifier in the common emitter configuration .Derive the expression for
the voltage gain of the amplifier.(5 marks)
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