Board Of Intermediate And Secondary Education Lahore F.A / F.sc Part II Physics Essay Type Past Paper 2012
Inter Part II Lahore Board 2012
Paper Physics | Paper II (Essay Type)
Time: 2.40 Hours Max Marks:68
2. Write short answers to any EIGHT (8) questions : 16
(i) How can you identify that which plate of a capacitor is positively charged?
(ii) If a point charge ‘q’ of mass ‘m’ is released in a non-uniform electric field with field lines pointing in the same direction, will it make a rectilinear motion?
(iii) When a dielectric slab is inserted between two oppositely charged parallel plates, what happens to electric field in the region between plates?
(iv) Compare e.m.f of a battery and potential drop across a conductor.
(v) How can a wheatstone bridge be used to determine unknown resistance? (Avoid details of wheatstone bridge)
(vi) Briefly discuss a circuit which will give continuously varying potential.
(vii) How can a current loop be used to determine the presence of a magnetic field in a given region of space?
(viii) Why is there no work done by magnetic field on a charge ‘q’ moving in it?
(ix) How will you convert a galvanometer into a voltmeter? Write formula for required resistance and explain terms used in it
(x) What is a commutator? What is its use?
(xi) Can an electric motor be used to drive an electric generator with the output of generator being used to operate motor?
(xii) When the primary of a transformer is connected to a.c. mains, the current in it:
(a) is very small if the secondary circuit is open but
(b) increases when the secondary circuit is closed. Explain these facts.
3. Write short answers to any EIGHT (8) questions: 16
(i) Define mutual1 inductance and its units.
(ii) Name the device that will (a) Permit flow of direct current but oppose the flow of alternating current (b) Permit flow of alternating current but not the direct current.
(iii) What is meant by AM and FM? Describe their frequency ranges.
(iv) A 100 uf capacitor is connected to an alternating voltage of 24 volt and frequency 50Hz. Calculate the reactance of die capacitor.
(v) What is meant by hysteresis loss? How is it used in the construction of a trans former?
(vi) Give the order of conductivity of: (a) Conductors, (b) Semi-conductors.
(vii) Differentiate between super conductors and high temperature super conductors,
(viii) The anode of a diode is 0.2 volt positive with respect to its cathode. Is it forward biased?
(ix) What is the principle of virtual ground?
(x) Draw the circuit symbol for: (a) n p n (b) p n p transistor
(xi) If an electron and proton have the some de Broglie wavelength, which particle has great
(xii) When does light behave as a wave When does it behave as a particle?
4. Write short answers to any SIX (6) questions: 12
(i) Give two postulates of special theory of relativity.
(ii) What is the energy of a photon in a beam of infrared radiation of wavelength 1240nm?
(iii) What do we mean when we say that atom is excited?
(iv) Write two postulates of Bohr’s model of H-atom.
(v) Explain why Laser action could not occur without population inversion between atomic levels.
(vi) What do you mean by the “dead time” of a Geiger counter?
(vii) What are Isotopes? What do they have in common and what are their differences?
(viii) A particle which produces more ionization is less penetrating, wiry?
(ix) How can radioactivity help in the treatment of cancer?
(SECTION – II)
Note: Attempt any THREE questions.
5.(a) State Gauss’s law and find electric intensity due to an infinite sheet of charge. 1,4
(b) A rectangular bar of iron is,2 cm by 2 cm in cross section and 40 cm lone. Calculate its resistance if the resistivity of iron is 11 x 10 Ω m. 3
6.(a) Define motional e.ntf. and derive a relation for it 5
(b) The magnetic field in a certain region is given by B = (40i-18k) Wbrn2. How much flux passes through a 5.0 cm2 area loop in this region if the loop lies flat in xy-plane? 3
7.(a) Explain conductors, insulators and semiconductors on the bases of energy band theory. 5
(b) What is the resonant frequency of a circuit which includes a coil of inductance 2.5 H and a capacitance of 40µF? 3
8. (a) Explain pair production and annihilation of matter. 5
(b) The current flowing into the base of a transistor is 100UA.
Find its collector current Ic and its emitter current IE if value of current gain is 100. 3
9.(a) What is nuclear reactor? Describe the function of its main parts. 1,4
(b) A tungsten target is struck by electron that has been accelerated from rest through 40 KV potential difference find the shortest wavelength of the bremsstrahlung radiation emitted.