12th physics question paper 2017 – bihar board
Section – I (Objective Type)
- The electrical intensity inside a charged hollow sphere is
(a)
(b) ![](https://lh6.googleusercontent.com/-3Ltt6ewlMmc6y8LqB5mWilCYljX6phtxiiIJxOL4BN3q2qRF-20UGETd96XHTxaNGNX-KROfRkkRiPPtdLRk4O2D5MjCuFYn967KV9Eg7ubGGaOj552NABu9lXkDwIKnW9y4lgRGeKAL_Bppw)
(c) Zero (d)
- Three capacitors each of capacity C are connected in series. The resultant capacity will be
(a)
(b) ![](https://lh4.googleusercontent.com/0pWk43z0olRBtUoVS4Yp3-EhEc8TLYhzAK3HSBb6WFeBwJsmzacxA69dpbxJW9x8lfu8Was6aZ9_CiRZ8H565EB4qCTbA3CdprKm0M4HUcgFhhmwg-k3cvlZSShtnyKAJ6vFU1UpaT0G_WrWyg)
(c)
(d)
- Two cells of emf
and
, internal resistance r1 and r2, connected in parallel. The equivalent emf of the combination is
(a)
(b) ![](https://lh6.googleusercontent.com/5lttXGS9qitihiFeuNFFULw80P7_C_qxGR-bM-cXHnh0OkEAu9wxaUzWkM0YkEaZQmcTmsJ6-SotYMO_YjlTcKXyoa4K_G3NHOswKCez3nUm3DExjAJSxktxCynYyQ-X4snsbHOTLNeD5CIwlA)
(c)
(d)
- Permeability µ of a ferromagnetic substance
(a) µ >> 1 (b) µ = 1
(c) µ < 1 (d) µ = 0
- S.I. unit of pole strength is
(a) N (b) N/A-m
(c) A-m (d) T
- Which element is used in electric heater?
(a) Copper (b) Platinum
- 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
- Wheat stone’s bridge is used in measuring
(a) High resistance (b) Low resistance
(c) Both high and low resistance (d) Potential difference
- 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
- The unit of rectangle is
(a) Ohm (b) Farad
(c) Ampere (d) Mho
- The relation between peak current I0 and root mean square current Irms is
(a)
(b) ![](https://lh4.googleusercontent.com/lEFX6pWezcl7HotzFDHx_Sj-femYuyy3tRX4PAdWbG-k2ThmsNcG1CwW0ba3EEY6LtlVwfe54GWZl5t1tNj99WhSveGC2EU6zk1nilV-pTn3RMwDEYWjcmDH5LQzC__da2pPPVtTdCT14zXNkQ)
(c)
(d) ![](https://lh6.googleusercontent.com/TCwarSkB-NwaMGTyOS3fi8lHhJcgUbArd2mjvMCEbAjZBubqBip05Vi8Xe3jsOqbXl86bAEWpctAfEPqfEzgqEKiDqi240SrAm6eKPSYKT_cAl9hvp0x5UAV4pLs7PBXI9iDhPHTHlaczWROZA)
- A short sighted person used for clear vision
(a) Convex Lens (b) Concave Lens
(c) Cylindrical Lens (d) Bi-focal Lens
- 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
- 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
- Transverse nature of light is shown by
(a) Interference (b) Reflection
(c) Polarization (d) Dispersion
- 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) ∞
- The direction of transmission of electromagnetic wave is
(a) Parallel to
(b) Parallel to ![](https://lh5.googleusercontent.com/AG8xm3gq9xDUD7Wb5qFg3SejwnsWaIzcmSSCahFHhUEx2XK0JiSn4evjCR2zh5kyoAZaBaAAJ45GWtMBMx8SWIeLq25SLpWEgAjGxvsFbA4s27qid7w-bLq1qE3MD0zTgHB0CvEc46eUiYrTlg)
(c) Parallel to
(d) Parallel to ![](https://lh4.googleusercontent.com/no4Do4jwWI4QiHbVC8th1ue4C6koWsryx9ufZJMu1sFhy8qX3KdMn61Jv_b3t1Z9Jb5t2jYA3aZbasGRyHhWP0S2Zp-uG4L-MkCwcnOPqEWtrMTWnT96VQcUAm8M850r-QYG6SuUYewmpjhp_g)
- 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
- 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
- Which one of following is charge less?
(a) Alpha particle (b) Beta particle
(c) Photon particle (d) Proton
- Which series of hydrogen spectrum does not lie in infrared region?
(a) Humphreys series (b) Pfund series
(c) Bracket series (d) Lyman series
- 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
- 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
- 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
- For n-type Germanium, impurity doped in Germanium is
(a) Trivalent (b) Tetravalent
(c) Pentavalent (d) None of these
- Diode is used as
(a) An amplifier (b) An oscillator
(c) A modulator (d) A rectifier
- Boolean expression for NAND gate is
(a)
(b) ![](https://lh5.googleusercontent.com/deLymBeTDAGtp3AS2mXoNGn9SkbD2av5uH2iW56FzB7j0X5_p5jROL3O4UE0YhYW4K5fwvLl5aY8hqO2U82HFMX_n3oSUhNyGwMFcRoP1cD3c92_sE_neZNsD1aVFmlgLsyDQVZ4P6kWCdmrLA)
(c)
(d) ![](https://lh3.googleusercontent.com/1nMXIVPjW9Seezox2J1BqItP95dIcXwigyKmESePIjcBc5LmmuJSd86D4lY3CExoGOpjNKQowExtwIbSOOMoA9f9GVmse_FNbnn0H93QP4--8g2sFMuzr7aM7yIL2oU-Tw16fX-7PDfthpTNHA)
- 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
Section – II (Non- Objective Type)
Short Answer Type Questions
- Draw lines of force of electric field due to a system of two equal point charges.
- Write expression for magnetic field B on axis and equator of a shot bar magnet.
- 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?
- Explain that Kirchoff’s second law is law of conservation of energy.
- 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.
- Write Brewster law of polarization of light.
- Show that a tangent galvanometer measures that current with maximum accuracy which produces 450 deflection.
- A bulb rates 100 W, 200 V is connected across 240 volt. Calculate electrical power loss.
- 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.
- Write change in position of atom of an element in periodic table due to emission of α and β particles from its nucleus.
- Explain modulation and write types of modulation.
Long Answer Type Questions
- 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.
- 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.
- 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.
- Explain: (i) Zener diode (ii) LED (Light Emitting Diode)
Or
- Explain constitution of atomic nucleus
- Write difference between nuclear fission and radioactivity.
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