# BSEB / Bihar Board 12th Exam Sample Paper Physics

Bihar School Examination Board (BSEB)

SAMPLE PAPER/MODEL TEST PAPER

SUBJECT  – PHYSICS

Class – 12th

Section – 1 (objective type)

1. In the following question NOs. 1 to 10 there are only one correct answer.
1. You have to choose that correct option:

(a) always zero                                         (b) between

(c) between 0 and infinitive                (d) none of these

2. The capacitance of a parallel plate capacitor ……… by the introduction of a dielectric between the plates of the capacitor.

(a) increases                                              (b) decreases

(c) remains same                                     (d) nothing can be said

3. The quantum of electric charge is e.s.u. is

(a) 4.78 * 1010 (b) + 1.6 * 10 -19

(c)  2.99 * 10 9 (d) – 1.6 * 10 -19

4. Electrostatic field is

(a) conservative                                          (b) non – conservative

(c) some where conservative and somewhere non – conservative

(d) none of these

(5) Which of the following ratios is constant for an isolated conductor?

(a) Total charge/ Potential                                  (b) Charge added/ Potential difference

(c) (Total charge) 2/ Potential                         (d) none of these

6. Kilowatt – hour (k Wh) is the unit of

(a) Power                          (b) Energy

(c) Torque                        (d) none of these

7. A charge moving with uniform velocity produces

(a) only an electric field                  (b) only a magnetic field

(c) Electromagnetic field                (d) none of these

8. SI unit of pole strength is

(a) N                                             (b) N/Am

(c) Am                                          (d) T

9.  Colombian force is

(a) central force                               (b) electric force

(c) both (a) and  (b)                    (d) none of these

10. If the uniform electric field exists along X – axis, them equipotential is along

(a) XY – plane                              (b) XZ – plane

(c) YZ – plane                                 (d) anywhere

II. In the following question Nos. 11 to 15, there are two statements. You have to go through these statements and choose the correct answer from the choices given below:

11. Consider the following statements:

Statement 1: Negaveir charge always moves form point of low potential to high potential.

Statement II: /electric potential is a vector quantity. Of these statements:

(a)   Both the statements are true and Statement II is the correct explanation of Statement I.

(b)  Both the statements are true, and Statement II is not the correct explanation of Statement I

(c)   Statement I are true, but Statement II is false

(d)  Statement I is false, but Statement II is true

12. Consider the following statements:

Statement I: The temperature coefficient of resistance is always positive.

Statement II: The resistance of metal and its alloys increases with the rise of temperature.

(a)   Both the statements are true and Statement II is the correct explanation of Statement I.

(b)  Both the statements are true, but Statement II is not the correct explanation of Statement I.

(c)   Statement I is true, but Statement II is false.

(d)  Statement I is false, but Statement II is true.

13. Consider the following statements:

Statement I: Potentiometer measures e.m.f.

Statement II: Voltmeter measures potential difference.

Of these statements:

(a)   Both the statements are true and Statement II is the correct explanation of Statement.

(b)  Both the statements are true, but Statement II is not the correct explantaiton Statement I

(c)    Statement I is true, but Statement II is false.

(d)   Statement I is true, but Statement II is true.

14. Consider the following statements:

Statement I: If the accelerating potential in an X – ray tube is increased, the minimum or cut – off wavelength of the X – rays produced remains unchanged;

Statement II: If the potential difference between electrodes in X – ray tube is increased, te intensity of the emitted radiations remains unchanged.

Of these statements:

(a)   Both the statements are true and Statement II is the correct explanation of Statement

(b)  Both the statements are true, Statement II is not the correct explanation of Statement I

(c)    State I is true , but Statement II is false

(d)   Statement I is false, but Statement II is true

15. Consider the following statement:

Statement I: Free neutron is not stable

Statement II: Outside the nucleus, a Bita neutron decays into a proton, an electron and an anti neutrino.

Of these statements:

(a)   Both the statements are true and Statement II is the correct explanation of Statement

(b)  Both the statement are true, but Statement Ii is not the correct explanation of Statement I

(c)    Statement I is true , but Statement II is false.

(d)   Statement I is false, but Statement II is true

III

In Question Nos. 16 to 18, there is only one correct answer among the four alternatives. You have to choose the correct option and mark it in the answer sheet.

16. Antenna is

(a) inductive                                         (b) capacitive

(c) resistive at resonant frequency             (d) resistive above resonant frequency

17. Two bulbs consume same power when operated at 200 V and 300 V respectively. When these two bulbs are connected in series across a D.C. source of 500 V, then at the ends of the two bulbs

(a) ratio of potential difference will be 3/2

(b) ratio of potential difference will be 4/9

(c) ration of power consumed will be 4/9

(d) ration of power consumed will be 2/3

18. To convert mechanical energy into electrical energy one can use

(a) D. c. dynamo                             (b) A.C. dynamo

(c) Motor                                        (d) Transformer.

IV. In the following question Nos. 18 to 22, there are two column. Columns I contains 4 question. You have to match the correct options of these question as (A) , (B), (C) and from Column II:

Column I                                   Column II

19. Photoelectric effect                              (A) Roentgen

20. X – ray                                              (B) Rutherford

22. Behavior of characteristic X – ray     (D) Moseley

V. For the following Question Nos. 23 to 25 a paragraph is given. You have to first go through that given paragraph and then answer the following there questions by indicating correct option. These questions Carry two marks each.

A lens is a piece of a transparent substance bounded but two surfaces, ort of which one must be curved. In a lens both the surfaces many also be curved. All the distances are measured form the optic centre. The direction of the incident ray taken as positive and the direction opposite to the incident ray is taken as negative. The refraction formula for spherical curved surface is

n2 /v – n1 / u = n2 – n1 /r and

The Gaussian formula for a lens is 1/v – 1 u = 1 / f

Image of different sizes and nature are formed by these surfaces of the lens and they depend on the positions of the object from the refracting surfaces.

23. The power of biconvex lens having the radius of curvature | r1| = |r2|= 40 cm of each surface and the refractive index of the material lens n = 3/2 will be

(a) 2.5 D                           (b) 0. 25 D

(c) 25 D                            (d) 0. 025 D

24. To obtain a real image of twice the size as that of the object by a converging lens of focal length 20 cm, an object must be placed at a distance of

(a) u = 20 cm                                    (b) u = – 50 cm

(c) u = – 30 cm                                   (d) none of these

25. If a converging lens is placed in a liquid having refracting index same as refractive index of the material of lens (n liquid = n lens), then its focal length

(a) will be infinite                           (b) will be small but non – zero

(c) remains unchanged                    (d) will become zero

Section II ( Non  – Objective type)

1. Question Nos. 1 to 11 are of the short type questions and each carries 2 marks
1. What is the limitation of Coulomb’s law?
2. Define Dielectric strength and Relative permittivity
3. What is a hysteresis loop?  With its help explain the terms ‘retentively’ and ‘coercivity’.
4. How is chromatic aberration reduced?
5. Explain any two of he following terms

(a) Ground waves                                 (b) Sky waves

(c) Space waves

6. Draw a circuit diagram of common emitter amplifier.

7. Explain the following:

(i) www                                (ii) Fax

7. What is the difference between Magnification and Magnifying power?

8. What is seeback effect

9. Why is internal resistance of a secondary cell low?

10. What are Polaroid? Mention its uses.

11. What will be the result, if a student connects voltmeter in series and ammeter    in parallel in a circuit by mistake?

12. Define capacitating and gives SI units. Prove that the total electrostatic energy stored in a parallel plate capacitor is ½ CV2. Hence derive the expression for the energy density of the electric field at its base.

Or, derive an expression for the capacitance of a parallel plate capacitor. If a compound dielectric medium is introduced between the plates of the capacitor, how will the capacitance of the capacitor change?

13. Draw a ray diagram to show the refraction of light through a glass prism. Derive the formula for the determination of refractive index of the material of the prim.

14. State Bohr’s assumption to explain the spectra of hydrogen – like atoms Obtains an expression for the total energy of an electron revolving in the nth stationary orbit of an atom.

15. What are energy hands is solids? How are semiconductors, insulators and conductors classified on the basis of band theory?

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