12th physics question paper 2013 – bihar board

Section – I (Objective Type)

1. How many images are formed by the lens if an object is kept on the axis?

(a) 1 (b) 2

(c) 3 (d) 7

2. 64 identical drops each of capacity 5µF combine to form a big drop. What is the new capacity of big drop

(a) 4µF (b) 25µF

(c) 20µF (d) 164µF

3. A current flows in a wire of resistance 5Ω having potential difference 7 volt for 20 minutes. The heat produced is

(a) 140cal (b) 280cal

(c) 700cal (d) 2800cal

4. The value of amplitude modulation index is

(a) always 0 (b) between 1 and ∞

(c) between 0 and 1 (d) always ∞

5. When a ray of light enters a glass slab its wavelength

(a) decreases (b) increases

(c) remains unchanged (d) data are not complete

6. The unit of reactance is

(a) mho (b) ohm

(c) farad (d) ampere

7. Write the decimal number 25 in binary

(a) (1100)2 (b) (1001)2

(c) (11001)2 (d) (11101)2

8. Which series comes in visible region of hydrogen spectrum?

(a) Lyman series (b) Blamer series

(c) Paschen series (d) Brackett series

9. The equivalent capacity between A and B is

(a) (b)

(c) (d)

10. The electric flux over the surface of a sphere if it is charged with 10µC is

(a) 36 x 104 Nm2/C (b) 36 x 10-4 Nm2/C

(c) 36 x 106 Nm2/C (d) 36 x 10-6 Nm2/C

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:

1. Both the statements are true and statement-II is the correct explanation of Statement-I
2. Both the statements are true, but Statement-II is not the correct explanation of Statement-I
3. Statement-I is true, but Statement-II is false
4. Statement-I s false, but Statement-II is true.

11. Statement-I: Photon cannot be deflected by magnetic and electric field.

Statement-II: Rest mass of photon is zero.

12. Statement-I: When a semiconductor is doped with impurities, its conductivity increases.

Statement-II: When a semiconductor is doped with impurities, its temperature increases.

13. Statement-I: The upper end of lightning conductor fitted on roof of a building is pointed.

Statement-II: It is done to increase the surface density of charge.

14. Statement-I: For focal length of a convex lens

Statement-II: The focal length of red colour of light is maximum.

15. Statement-I: The diode shown in figure is Zener diode.

Statement-II: Zener diode works as reverse bias.

III. In Question Nos. 16 to 18, there may be more than one correct answer among the four alternatives. You have to choose all the correct options and mark in the answer sheet.

16. The S.I. unit of electric field is

(a) Cm-2 (b) NC-1

(c) Am (d) Vm-1

17. Image formed by a concave spherical mirror is

(a) virtual (b) real

(c) magnified (d) inverted

18. In photoelectric effect the maximum kinetic energy of emitted electron depends on

(a) wavelength (b) frequency

(c) intensity (d) work function

IV. In the following Question Nos. 19 to 22, there are two columns. Column-I contains 4 questions. Our have to match the correct options of these questions (A), (B), (C) and (D) from Column-II.

Column-I Column-II

19. Ohm’s law (A) Potential difference x current
20. Kirchhoff’s law (B) Potential difference x current x time
21. Force X Velocity (C) Potential differenceCurrent=constant
22. Kilowatt-hour (kWh) (D) Conservation of energy

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 three questions by indicating correct option. These questions carry tow marks each.

Paragraph

When a ray passes through a prism, refraction takes place as shown in figure:

 

Here A is the angle of prism.

NO is perpendicular on point X. N’O is perpendicular on point Y.

23. Angle of emergence is

(a) <i1 (b) <i2

(c) <r1 (d) <r2

24. Angle a is

(a) (b)

(c) (d)

25. When a ray passes symmetrically through a prism it suffers minimum deviation. Here is

(a) <A (b) 2A

(c) (d)

Section – II (Non- Objective Type)
12th physics question paper 2012 – Bihar board

Short Answer Type Questions
12th physics question paper 2014 – Bihar board

1. Define electric field intensity in current carrying conductor and equipotential surface.
2. Write two main features of LASER rays.
3. Two condensers have capacitances C1 and C2. Show their parallel combination and series combination circuits.
4. Define mean value and root mean square value of alternating current.
5. The powers of two lenses are +12D and- 2D. They are placed in contact on the same axes. What will be the focal length of the combination?
6. Write any two properties of X-rays.
7. Distinguish between n-type and p-type semiconductors.
8. Write Lenz’s law of electromagnetic induction.
9. What is transformer? What do you mean by its efficiency?
10. What is de-Broglie wave? Write an expression for its wavelength.
11. What do you mean by Eddy currents?

Short Answer Type Questions

12. Write Huygens principle of light wave. Prove the laws of reflection or refraction of light on the basis of Huygens principle of light.

Or

The minimum angular magnification of an astronomical telescope is 10X. The length of its tube is 44cm. Determine the focal length of the objective lens

13. Give a brief account on the means of communication.

Or

1. What do you mean by analog and digital signals?
2. What is amplitude modulation? Explain.

14. Explain with a neat diagram, the working of a compound microscope. Obtain an expression for its magnifying power.

Or

Show for a prism that the refractive index n is given by

, Where symbols have their usual meaning.

15. Explain the band theory of solids. State how on this basis solids are classified into conductors, insulators and semiconductors.

Or

p-n junction is a valve. Explain.

In a band structure of p-type semiconductor, acceptor energy level lies 57 MeV above the valence band. Find the maximum wavelength of light, which can create an acceptor hole. (Given h= 4.14x10-15 eV,c= 3x108ms-1)