PHYSICS PAPER 12TH CLASS 2019 SARGODHA BOARD GROUP 1

PHYSICS PAPER 12TH CLASS 2019 SARGODHA BOARD GROUP 1 OBJECTIVE

Physics	Sargodha Board 2019	Group 1
Maximum Marks: 17	Objective Type	Time Allowed: 20 Mints

(i)         Types of quarks are:

            (a) 2                 (b) 4                 (c) 6                 (d) 8

(ii)        In liquid metal fast breeder reactor the type of uranium used is

            (a) ²³⁵ U₉₂           (b) ²³⁸ U₉₂        (c) ²³⁴ U₉₂         (d) ²³⁹ U₉₂

(iii)       The force between two charges is 28N. The paraffin was of relative permittivity 2.8 is introduced between the charges as medium then force reduces to

            (a) 25 N           (b) 20 N           (c) 10 N           (d) 15 N

(iv)       A charge of 10-10 C between two parallel plates 1 cm apart experienced a force of 10-5 N. The p.d. between the plates is

            (a) 10 V           (b) 10² V         (c) 10³ V          (d) 10⁴ V

(v)        Tolerance for silver colour is

            (a) +10%         (b) +15%         (c) +20%         (d) +5%

(vi)       Two parallel wires carrying currents in opposite direction.

            (a) Repel each other    (b) Attract each other  (c) Neither attract nor repel     (d) Stick to each other

(vii)      A 5m wire carrying current 2 A at right angle to uniform magnetic field 0.5 T. The force on the wire is

            (a) 1.5 N          (b) 5 N             (c) 2.5 N          (d) 4 N

(viii)     If the coil is wound on iron core, the flux through it

            (a) Decreases   (b) Become zero          (c) Remains constant   (d) Increases

(ix)       Energy stored per unit volume in magnetic field is called

            (a) Energy density       (b) Electric flux           (c) work           (d) Power

(x)        S.I unit of magnetic field is called     

            (a) Farad          (b) volt                        (c) ampere                   (d) tesla

(xi)       The device which allows only the flow of D.C. is

            (a) Capacitor               (b) Resistor                  (c) Inductor     (d) Generator

(xii)      A vacant or partially filled band is called

            (a) Fermi Band            (b) Valence Band        (c) Forbidden Band    (d) Conduction Band

(xiii)     For normal operation of transistor, the Emitter-Base junction is always

            (a) Forward Biased     (b) Reverse Biased      (c) Unbiased    (d) Grounded

(xiv)     The S.I unit of current gain is

            (a) Volt            (b) Ampere                  (c) Coulomb                (d) No unit

(xv)      The factor h/mc in in Compton effect has the dimensions of

            (a) Pressure      (b) Length                   (c) Mass                       (d) Momentum

(xvi)     The materialization of energy takes place in the process of

            (a) Photoclectric effect           (b) Compton effect     (c) Pair production      (d) Annihilation of Matter

(xvii) Joule-second is the unit of

            (a) Energy       (b) Heat           (c) Plank’s constant                 (d) Power

PHYSICS PAPER 12th CLASS 2019 SARGODHA BOARD GROUP 1 SUBJECTIVE

BISE Sargodha, BISE Sargodha Past Papers

Physics	Sargodha Board 2019	Group 1
Maximum Marks: 68	Subjective Type	Time Allowed: 2.40 hours

Subjective Type Section-I

Q.2      Write short answers to any Eight (8) questions:

            (i) Define Electrostatics and Xerography.

(ii) Define Gaussian surface and electric lines of force.

(iii) The potential is constant throughout a given region of space. Is the electric field is zero or non-zero is this region? Explain.

(iv) How can you identity that which plate of a capacitor is positively charged.

(v) Define magnetic induction and tesla.

(vi) Define magnetic flux and flux density.

(vii) Why the resistance of an ammeter should be very low?

(viii) Why the voltmeter should have a very high resistance.

(ix) Define electromagnetic induction and induced emf.

(x) Define mutual induction and Henry.

(xi) Four unmarked wires emerge from a transformer. What steps are required to be done.

(xii) Can a D.C motor be turned into a D.C? What changes are required to be done?

Q.3      Write short answers to any Eight (8) question:

(i) What is Wheatstone bridge? How can it be used to determine an unknown resistance?

(ii) Is the Filament resistance lower or higher in a 500 W, 200 V light bulb than in a 100 W, 220 V bulb?

(iii) Define sources of current and give its two examples.

(iv) Explain the conditions under which electromagnetic waves are produced from a source?

(v) What is meant by A.M and F.M?

(vi) What is choke? Explain.

(vii) Explain the term Hysteresis.

(viii) Define stress and strain. What are their SI units?

(ix) What are superconductors? Write their types.

(x) What is the biasing requirement of the junction of a transistor for its normal operation? Explain how these requirements are met in a common emitter amplifier?

(xi) The anode of a diode is 0.2 V positive with respect to its cathode. Is it forward biased?

(xii) Write two characteristics of operational amplifier.

Q4.      Write short answers to any Nine (9) questions:

(i) What advantages an electron microscope has over an optical microscope?

(ii) Can pair production take place in vacuum? Explain.

(iii) Find the energy of photon in radio wave of wavelength 100m.

(iv) Define excitation energy and ionization energy.

(v) Can X- rays be reflected, refracted, diffracted and polarized just like any other waves? Explain.

(vi) Explain briefly fission chain reaction.

(vii) How can radioactivity help in the treatment of cancer?

(viii) Define hardons. Also differentiate between baryons and mesons.

(ix) What information is revealed by the length and shape of the track of an incident particle in Wilson could chamber?

SECTION-II

Note:   Attempt any THREE questions.

Q.5      (a)What is electric potential? Find electric potential at a point due to a point charge.

            (b) A rectangular bar of iron is 2.0 cm by 2.0 cm in cross section and 40 cm long.

            Calculate its resistance if the resistivity of iron is 11 x 10^-8Ωm.

Q.6      (a) What is A.C Generator? Discuss the principle, construction and working of an A.C. Generator. Also find expression for induced emf and current.

            (b) How fast must a proton move in a magnetic field of 2.50 x 10^-3 T such that the magnetic force is equal to its weight?

Q.7      (a) Describe R-L-C series circuit, derive the expression for its resonance frequency and write down its properties.

            (b) In a certain circuit, the transistor has a collector current of 10mA and a base current of 40uA. What is the gain of the transistor?

Q.8      (a) What is Doping, Explain formation of n-type and p-type semiconductor?

            (b) An electron is placed in a box about the size of an atom that is about 1.0 x 10^-10 m. What is the velocity of the electron?

Q.9      (a) What is nuclear reactor? Describe its principle, construction, and working.

            (b) The wavelength of K X-ray from copper is 1.377 x 10^-10 m. What is the energy difference between the two levels from which this transition results?