# West Bengal Board Class 12 Physics Sample Papers 2011

## West Bengal Board Sample Papers 2011 for Class 12 Physics

Class 12
Sample Paper Of Physics

Time : 3. 00 Hours] [Maximum Marks : 100

Instructions :
(1) There are four sections and total 60 questions in this question paper.
(2) All symbols used in this question paper have their usual meanings.
(3) Log table or Simple calculator can be used.
(4) Begin new section on new page. Write answers in sequence.

1. Write the dimensional formula of Electric Potential.

2. Define Electric Susceptibility.

OR

Write any one use of Van-de-Graaff Generator.

3. Write Ohm's law.

4. What is Missner effect?

5. What is.Thermo electric power?

6. State one limitation of Cyclotron.

OR

State the principle of a Galvanometer.

7. What is called a Permanent magnet?

8. Draw the circuit symbol of an Inductor.

9. Name the electro-magnetic wave, which is used in Communication.

10. If for given medium, Critical angle is 30°, find the refractive index of the medium.

OR

If power of lens is +2 .0 D, then what will be the focal length of the Convex lens.

11. Write the condition of destructive interference in terms of path difference.

12. Draw the plane of vibration and plane of polarization in one figure.

OR

Give two definitions of Diffraction.

13. Write the formula of momentum for a Photon having frequency f-

14. Name the spectral series which lies in ultra-violet region of hydrogen spectra.

15. Write the boolean expression for the NOR gate.

16. What is Remote Sensing?

OR

17. Write four characteristics of electric field lines.

OR

Derive formula of energy stored in a charged capacitor.

18. Write Kirchhoff' s First law and derive it.

19. With necessary circuit diagram, explain charging process of Lead Storage Cell.

20. Write Biot Savart' s law and explain it.

21. Using Ampere's circuital law, derive the formula of magnetic field due to very long conductor carrying electric current. Draw necessary figure.

22. What is Motional emf ? Derive formula for motional emf.

23. In an A.C. circuit; L, C and R are connected in series . Derive formula for Power P-Vrms Irms cos S in such a circuit.
In a circuit; L, C and R are connected in series and A.C. voltage is applied. Derive the differential equation of charge Q in such a circuit.

24. Explain inductive components and radiated components with necessary diagram.

25. Derive the formula of Lateral magnification for a Concave mirror.

26. Write and explain Huygen' s principle with one example.

OR

Explain first order minimum in Fraunhoffer diffraction and obtain condition for it.

27. Explain it and 6 components in polarization by reflection. Write Brewster's law.

28. Write any four characteristics of a Photon.

29. Write Bohr's First Hypothesis. Derive formula of radius of nth orbit

OR

Write four limitations of Bohr model.

30. Name the unit of mass and energy in atomic and nuclear physics and define them.

31. Explain Half Wave Rectification with necessary circuit diagram and graph.

32. Explain Analog and Digital Communication.

33. A charge of 4x10-8 C is uniformly distributed all over the surface of a sphere of radius 1 cm. Another hollow sphere of radius 5 cm is concentric with smaller sphere. Find intensity of electric field at a distance of 2 cm from the centre.
K= 9x109SI.

34. A 900 pF capacitor is charged with the help of 100 V battery. Calculate the steady electric energy on this capacitor. The above capacitor is disconnected from the battery and is connected to another identical capacitor. What will be the total energy of the system?

OR

q, = 2µC electric charge is placed at origin of Cartesian Co-ordinate System. Another q2 =- 3µC charge is placed on the X-axis at a distance x =100 cm. At which points along the X-axis, will be the electric potential equal to zero?

35. An emf of 412.5 µV is developed in a Fe-Cd thermo-couple when its cold junction is at 0°C and hot junction at 30°C. When hot junction is kept at 100°C, 1200µV emf is produced, then find constants a and 0 of thermo-couple.

36. A toroidal core with 3000 turns has inner and outer radii of 11 cm. and 12 cm.respectively. When a current of 0.70 A is passed , then the magnetic field produced in the core is 2.5 T. Find the relative permeability of the core.
( go = 4n x 10-7 Tm A-').

37. A conducting bar of 2 m length is allowed to fall freely from a 50 m high tower,keeping it aligned along the east-west direction. Find the em f induced in the rod, when it is 20 m below from the top of the tower. g =10ms 2, Horizontal component of earth's magnetic field is 0.7 x 10-4 T and angle of Dip = 60°.

38. An A.C. source of 230 V is connected in series with 5 H inductor, 80 µ F capacitor and a 40 52 resistor.

(i) Find resonant frequency (fo).

(ii) Find the impedence of the circuit and the value of the current at resonant frequency.

OR

L and R are connected in series with an AC voltage. The maximum value of the AC voltage is equal to 220 V. Calculate the power consumed in the circuit as well as the power factor. The reactance of the coil is equal to 40 52 and R 30 Q.

39. When a linear object is placed in front of a convex mirror, image of the 4th size of the object is formed. Calculate the object distance and the image distance. This linear object is kept perpendicular to the axis.

OR

In Young's experiment, a beam of light of wave-length 6500 A and 5200 A is used. Find the maximum distance from the central bright fringe, where bright fringes produced by both the wave-length get super-posed. The distance between the two slits is 0.5 mm and the distance between the slits and screen is 100 cm.

40. Ultra-violet light of wave-length 200 nm is incident on polished surface of Fe.Work Function of the surface is 4.7 eV

Find .-

(i) Stopping Potential;

(ii) Maximum Kinetic energy of Photo electrons.

(h = 6.6x 10-34 J. sec., C = 3 x 108 ms 1, 1 eV = 1. 6 x 10-19 J.,m = 9.1 x 10-31 Kg.)

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