12th physics question paper 2017 – bihar board

Section – I (Objective Type)

1. The electrical intensity inside a charged hollow sphere is

(a) (b)

(c) Zero (d)

2. Three capacitors each of capacity C are connected in series. The resultant capacity will be

(a) (b)

(c) (d)

3. Two cells of emf and , internal resistance r1 and r2, connected in parallel. The equivalent emf of the combination is

(a) (b)

(c) (d)

4. Permeability µ of a ferromagnetic substance

(a) µ >> 1 (b) µ = 1

(c) µ < 1 (d) µ = 0

5. S.I. unit of pole strength is

(a) N (b) N/A-m

(c) A-m (d) T

6. Which element is used in electric heater?

(a) Copper (b) Platinum

(c) Tungsten (d) Nichrome

7. Absorbed electrical energy is

(a) Proportional to the potential difference

(b) Inversely Proportional to the potential difference

(c) Proportional to the square of the potential difference

(d) Potential difference

8. Wheat stone’s bridge is used in measuring

(a) High resistance (b) Low resistance

(c) Both high and low resistance (d) Potential difference

9. If the equation of an electric current is I=0.6 sin 100 , the frequency of electric current is

(a) 50 (b) 50

(c) 100 (d) 100

10. The unit of rectangle is

(a) Ohm (b) Farad

(c) Ampere (d) Mho

11. The relation between peak current I0 and root mean square current Irms is

(a) (b)

(c) (d)

12. A short sighted person used for clear vision

(a) Convex Lens (b) Concave Lens

(c) Cylindrical Lens (d) Bi-focal Lens

13. The critical angle of light passing rom glass to air is minimum for

(a) Red Colour (b) Green Colour

(c) Yellow Colour (d) Violet Colour

14. The angle of minimum deviation for thin prism of refractive index (µ) is

(a) (1- µ) A (b) (µ-1) A

(c) (µ+1) A (d) (µ+1) A2

15. Transverse nature of light is shown by

(a) Interference (b) Reflection

(c) Polarization (d) Dispersion

16. The focal length of a lens µ= 1.5 in air is 20cm. Its focal length in medium of refractive index 1.5 is

(a) 20 cm (b) 40 cm

(c) 10 cm (d) ∞

17. The direction of transmission of electromagnetic wave is

(a) Parallel to (b) Parallel to

(c) Parallel to (d) Parallel to

18. The unit of ratio of magnetic field B and electrical field E(B / E) is

(a) ms-1 (b) sm-1

(c) ms (d) ms-2

19. The energy of emitted photo electron depends upon

(a) Intensity of light (b) Wave length of light

(c) Work-function of metal (d) None of these

20. Which one of following is charge less?

(a) Alpha particle (b) Beta particle

(c) Photon particle (d) Proton

21. Which series of hydrogen spectrum does not lie in infrared region?

(a) Humphreys series (b) Pfund series

(c) Bracket series (d) Lyman series

22. The energy of electron in first Bohr orbit of hydrogen atom is – 13.6 eV. What is energy of electron in its 2nd Bohr-orbit.

(a) -3.4 eV (b) -6.8 eV

(c) -27.2 eV (d) +3.4 eV

23. Time during which the amount of radioactive substance becomes half of its initial amount is called.

(a) Average life (b) Half life

(c) Decay constant (d) Time period

24. β- Rays are deflected in

(a) Gravitational field (b) Only in magnetic field

(c) Only in electrical field (d) In magnetic and electric field both

25. For n-type Germanium, impurity doped in Germanium is

(a) Trivalent (b) Tetravalent

(c) Pentavalent (d) None of these

26. Diode is used as

(a) An amplifier (b) An oscillator

(c) A modulator (d) A rectifier

27. Boolean expression for NAND gate is

(a) (b)

(c) (d)

28. The height of a TV transmission tower at any place on the surface of the earth is 245m. The maximum distance up to which transmission of tower will reach is

(a) 245 m (b) 245 Km

(c) 56 Km (d) 112 Km

12th physics question paper 2016 – Bihar board

Section – II (Non- Objective Type)

Short Answer Type Questions

1. Draw lines of force of electric field due to a system of two equal point charges.
2. Write expression for magnetic field B on axis and equator of a shot bar magnet.
3. Potential due to a system of charge is V= 3 + 2x in S.I. system. What will be value of electric field at x= 2m?
4. Explain that Kirchoff’s second law is law of conservation of energy.
5. A point object is placed above principal axis at a distance three times focal length of a convex lens. Draw ray diagram showing position of image.
6. Write Brewster law of polarization of light.
7. Show that a tangent galvanometer measures that current with maximum accuracy which produces 450 deflection.
8. A bulb rates 100 W, 200 V is connected across 240 volt. Calculate electrical power loss.
9. A light of wavelength 600 Å is incident on a metal of work function 2eV. Will electrons be emitted? If yes, find maximum energy of emitted electron.
10. Write change in position of atom of an element in periodic table due to emission of α and β particles from its nucleus.
11. Explain modulation and write types of modulation.

Long Answer Type Questions

12. Deduce coulomb’s law from gauss law.

Or

Explain potential energy of a charge system. Calculate energy needed to place charge q at each corner of a square of side l.

13. An object is at infinity from a plan convex lens whose plane surface is silvered. Explain formation of its image and hence find its focal length.

Or

What is bi-prism? Explain measurement of wavelength of monochromatic light using bi-prism.

14. What is Wheatstone bridge? Explain its use in detail.

Or

Find time period of a bar magnet oscillating freely in a uniform magnetic field B.

15. Explain: (i) Zener diode (ii) LED (Light Emitting Diode)

Or

1. Explain constitution of atomic nucleus
2. Write difference between nuclear fission and radioactivity.