Physics Short Questions Guess Paper FSC 12th Class 2017
Note: (2nd Year Physics Guess Paper 2017) All published material contains an informatory data which is only gathered for educational purpose. These guesses are prepared after detailed analysis of past five years exams. Our entire team and/or publishers are not responsible in case of variation in assumed results and outcomes. However the purposes of attempted efforts are to provide accurate and effective knowledge to the readers, in any case our entire team and/or publishers will not be responsible for the accuracy or misusage of all published material.
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Frequently Asked Questions (2012 to 2016)
Define torsional couple.
Describe the digital system
Explain frame of reference? OR What is the relativistic time measured in a frame of reference moving with velocity?
What is annihilation of matter? OR Explain pair production and annihilation of matter
Explain photovoltaic cell?
How heat is dissipated across any load or resistor?
If r is a unit vector directed from the point charge q to the test point where. OR Write a note on Vector representation of an alternating quantity.
What is Gaussian surface?
What is half-wave rectification?
What is mutual induction?
What is polymeric solid?
What is proper length?
What is right-hand rule?
What is the chemical formula of Yttrium barium copper oxide?
What is the speed of a-particles at which they hit the gold foil?
What is the working principle of a LED?
When ultraviolet light falls on certain dyes, visible light is emitted. Why does this not happen when infrared light falls on these dyes?
Write a note on Phase lag and phase lead.
Write a note on Wilson Cloud Chamber?
Write the types of spectra?
How can you identify that which plate of capacitor is positively charged? OR When the capacitance of the capacitor is one farad? OR How does doubling the frequency affect the reactance of an inductor and a capacitor?
What are isotopes? Write some uses of isotopes. OR How can you use a magnetic field to separate isotopes of chemical element? OR What are isotopes? What do they have in common and what are their differences?
What is shunt resistance? Explain briefly. OR What is the Principle of measuring the Unknown resistance by the wheat stone bridge? OR What is the heat H produced by a current I in the wire of resistance R during a time interval? OR Is the filament resistance lower or higher in a 500 W, 220 V light bulbs than in 1.00 W. 220 V bulbs? OR Do bends in a wire affect its electrical resistance? Explain. OR Why a voltmeter should have a very high resistance? OR The resistance of a condUctor rises with temperature. Explain why? OR Why does the resistance of a conductor rise with temperature? OR What is wheatstone bridge? How can it be used to determine the unknown resistance? OR Do bends in a wire affect its electrical resistance? Explain.
What is back emf in motor? OR What is the net current flowing through the coil of a motor in the presence of back emf? OR What is the induced emf produced during the phenomena of mutual induction? OR A metal rod of length 25 cm is moving at a speed of 0_5 MC in a direction perpendicular to a 0 25 T magnetic field. Find the emf produced in the rod Under what conditions the terminal P.D. is greater than emf of battery? OR Define induced current and induced emf. OR What is motional emf? Give its formula. OR How would you position a flat loop of wire in a changing magnetic field so that there is no emf induced in the loop? OR A square loop of wire is moving through a uniform magnetic field. The normal to loop is oriented parallel to magnetic field. Is emf induced in loop? Give a reason for your answer.
Does the voltage output of a generator change if its speed of rotation is increased? Explain briefly. OR What is the voltage measuring part of the AVO meter? OR Two equal resistors are first connected in series and then in parallel to the same voltage source. OR An A.0 Voltmeter reads 250 V. What is its peak and instantaneous values if the frequency of alternating voltage is 50 Hz? OR How does the voltage output of a generator change?
State and briefly explain Kirchoff’s first rule (current law). OR State Kirchoff s first rule and second rule.
What is meant by A.M. and F.M.? OR What are transmission frequencies for electromagnetic waves in (a) A.M. range (b) F. M. range?
What is choke? What is its main use? OR Define choke and give its unit.
Define stress and strain. OR Define stress and differentiate between volume stress and shear stress. OR What is the stress if the force F is applied on unit area A? OR Define modulus of elasticity. Show that units of modulus of elasticity and stress are same. OR Show that the units of modulus of elasticity and stress are the same. OR Define ultimate tensile strength (UTS) and fracture stress. OR Define stress and strain. What are their SI units?
What are super conductors? OR Write the uses of super conductors. OR Draw figure showing electrical conduction by holes in semi-conductor. OR What is the behavior of semi-conductor diode at zero Kelvin? OR Explain briefly the conductors on the basis of energy band theory. OR Give the order of conductivity of (a) conductor (b) semi-conductor. OR Describe briefly the formation of energy bonds in semi-conductor. OR Distinguish between intrinsic and extrinsic semi-conductor? OR Distinguish between conductor insulator and semi-conductor with the help of energy bond theory. OR What is difference between intrinsic and extrinsic semi conductors?
Define amorphous solids? OR Distinguish between crystalline and polymeric solids. OR Distinguish between crystalline and amorphous solids.
What are diamagnetic substances? OR How does motion of an electron in n-type substance differ from motion of hole in p-type substance? OR Define diamagnetic paramagnetic and Ferro magnetic substances. OR What is meant by paramagnetic substances? Give examples. OR What is net charge on N-type and P-type substances? OR Differentiate between ductile and brittle substances. Give an example for each.
Write down symbol and truth table of exclusive NOR gate.
Which photon blue or red has greater energy and greater momentum? OR Photon A has twice the energy of Photon B. OR What is the ratio of momentum of A to that of In Which photon blue or red has greater energy and greater momentum? OR From the theory of relativity, how the momentum p of the photon is related to energy?
State any two postulates of Bohr atomic theory. OR Do any of Bohr’s postulates contradict classical Physics? OR Write down the postulates of special theory of relativity. OR Write any two postulates of Bohr’s theory.
Write any four uses of laser. OR Write some uses of laser in medicine and industry. OR What are the advantages of lasers over ordinary light? OR Explain why laser action could not occur without population inversion between atomic levels?
What factors make a fusion reaction difficult to start? OR What factors make a fusion reaction difficult to achieve? OR State the advantages and disadvantages of fusion power from the point of view of safety pollution and resources.
Define Decay constant. OR Half life of Sr is 9.70 hours. Find its decay constant. OR Define decay constant and write its unit. OR If a nucleus has half life of one year does this mean that it will completely decay after two years? OR Define half life of a radio active element. Also write the relation between half life and decay constant.
Write down the half life of radium 226 and radon gas.
Electric lines of force never cross. Why? OR Electric lines of force never cross one another. Why?
Why does the picture on a T.V. screen become distort when a magnet is brought near the screen? OR Why does the picture on a T.V. screen become distorted when a magnet is brought near it?
What is dead beat galvanometer? OR What is stable or dead beat Galvanometer? OR What is current sensitivity of a suspended moving coil galvanometer? How does it depend upon different factors? Describe by mathematical formula. OR What is cathode ray oscilloscope and galvanometer? OR Define current sensitivity of a galvanometer.
What is magnetic induction? Define its unit. OR What should be the orientation of a current carrying coil in a magnetic field so that torque acting upon the coil is: a. Maximum, b. Minimum? OR What is the force experienced by a current carrying rod placed in an external magnetic field if the rod is placed parallel to the field? OR There exists a magnetic held of 0.30 T in space along +X-axis. What will be the magnetic force on a proton of q = 1.6 x 10-19C , when it is moving with velocity 3. OR How the magnetic field of the solenoid is found? OR How the magnetic field in the D.C. motor is provided? OR How can a current loop be used to determine the presence of a magnetic field in a given region of space? OR Explain the existence of magnetic domains in Ferromagnetic material. OR Describe the change in magnetic field inside solenoid carrying a steady current I, if length of solenoid is doubled but number of turns remains the same. OR Describe right hand rule to find the direction of lines of magnetic field. OR Describe Faraday’s law of electromagnetic induction. OR Explain the conditions under which electromagnetic waves are produced from a source. OR Two charged particles are projected into a region where there is a magnetic field perpendicular to their velocities. If the charges are deflected in opposite directions, what can you say about them? OR Is it possible to orient a current loop in a uniform magnetic field such that the loop will not tend to rotate? Explain. OR In a certain region the earth’s magnetic field points vertically downward. When a plane flies due north, which wingtip is positively charged? OR Explain working of a heater that works on the principle of electromagnetic induction. OR Describe the change in magnetic field inside solenoid carrying a steady current 1, if length of solenoid is doubled but number of turns remains the same. OR What are ferromagnetic substances? Give an example.
For unmarked wires emerge from a transformer. What steps would you take to determine the turns ratio? OR Find the magnitude of the force acting on the wire. OR Decreasing the length and the temperature of the wire. OR A charge of 90 coulomb passes through a wire in one hour and fifteen minutes. What is the current in the wire?
State Faraday’s law. OR State Gauss’s law. OR Describe Lenz’s Law. OR Coulomb’s law for electrostatic charges. OR Which law is applied to calculate the electric intensity due to different charge configuration? OR Does the filament of a lighted bulb obey Ohm’s law? OR Define Ohm’s law. Also define ohmic and non ohmic devices.
What is electromotive force and give its units? OR What is meant by an electromotive force, give its unit?
What is resonance condition? OR Define impedance and resonance frequency. OR Define resonance frequency. Give its equation.
How many times per second will an incandescent lamp reach maximum brilliance when connected to 50 Hz source?
Explain inductive reactance? OR Define reactance of an inductor and write its formula. OR How does doubling the frequency effect the reactance of: (a) An inductor (b) a capacitor? OR At what frequency will an inductor of 1.0 H have a reactance of 5000?
What is meant by strain energy? Give its relation. OR How the strain energy can be obtained?
Write four uses of photo diode. OR What is the effect of forward and reverse biasing of a diode on the width of depletion region? OR How is depletion region formed in PN-junction diode? What is the effect on the width of depletion region when: a. Diode is forward biased, b. Diode is reverse biased. OR Give the four applications of a photo diode. OR Why a photo diode is operated in reverse biased state. OR Why photodiode is operated in reverse biased state? OR Why ordinary silicon diode does not emit light?
Why charge carriers are not present in depletion region?
What is current gain of transistor? OR What is the current gain of the transistor? OR Why is the base current in a transistor very small?
Why the radio waves are detected as continuous radiation? OR What are black body radiations? OR What happens to total radiation from a blackbody if the absolute temperature is doubled? OR What do you understand by background radiation? OR Compute the shortest wavelength radiation in the Balmer series. OR Calculate the longest wavelength of radiation for the Paschen series. OR Which radiation dose would deposit more energy to the body (a) 10mGy to the hand or (b) I mGy dose to the entire body? Explain why? OR Describe a brief account of interaction of various types of radiations with matter.
What do we mean by the term critical mass? OR Define critical temperature and curie temperature.
Write the two statements of uncertainty principle. OR How the uncertainty principle between energy and time is related? OR State uncertainty principle. Give its two mathematical forms.
Is energy conserved when an atom emits a photon of light? OR What do we mean when we say that the atom is excited? OR Bohr’s theory of hydrogen atom is based upon several assumptions. Do any these assumptions contradict classical physics? OR Atomic number or the charge number of an atom? OR Applying the second postulate of Bohr’s Model of Hydrogen Atom, derive the relation for Quantized Radii of hydrogen atom. OR What is the difference between excitation of an atom by (a) a photon (b) an electron?
Define electron volt. OR As a solid is heated and begins to glow, why does it first appear red? OR Is it possible to create a single electron from energy? Explain. OR Will higher frequency light eject greater number of electrons than low frequency light? Explain briefly. OR Convert 1 joule into electron volt. OR What is one electron volt energy? Derive its formula. OR If an electron and a proton have the same de Broglie wavelength, which particle has greater speed? OR How many are the number of electrons in one coulomb charge? OR How can the spectrum of hydrogen contain so many lines when hydrogen contains one electron? OR Find the speed of the electron in the first Bohr Orbit. OR Determine charge to mass ratio (e/m) of an electron. OR Can electron in the ground state of hydrogen absorb a photon of energy 13.6 ev and greater than 13.6 ev? OR Differentiate an orbital electron from a free electron. OR What advantage an electron microscope has over an optical microscope? OR Define conventional current and electronic current.
What advantaees of an electron microscope has over an optical microscope?
What is meant by the term ‘meter movement’?
What are the uses of CRO?
What are thermisters? Give their uses.
What is meant by Hysteresis loss? How is it used in the construction of a transformer? OR What is hysteresis loop? Describe its main features.
A particle which produces more ionization is less penetrating. why?
What do you mean by Lorentz force? OR What is Lorentz force and how can it be formulated?
Write the principle of electric generator. OR What is function of sweep generator in cathode ray oscilloscope? OR Name the main components or parts of an A.C. generator. OR Can a D.C. motor be turned into a D.C. generator? What changes arc required to be done? OR How does the construction of a DC generator differ from AC generator? OR What are the differences between motor and a generator? OR When an electric motor, such as an electric drill, is being used, does it also act as a generator? If so what s the consequence of this?
What is the maximum power output theorem? Derive its formula. OR In a transformer, there is no transfer of charge from the primary to the secondary. How is, then the power transferred? OR How is then the power transferred? OR Define electric power. Obtain the maximum power equation. OR Can a step up transformer increase the power level?
Which charges actually flow in case of conventional current?
State Krichhoff’s loop rule.
How the reception of a particular radio station is selected on your radio set? OR How can radioactivity help in the treatment of Cancer? OR What is radioactive tracer? OR Describe an application each in medicine, agriculture, and industry. OR Define half-life of a radioactive element. OR Which has the lower energy quanta? Radio waves or X-rays. OR What is radio active tracer? Describe one application in medicine.
What is squid and where is it used?
Write down the characteristics of operational amplifier. OR What is the principle of virtual ground? Apply it to find the gain of an inverting amplifier.
Draw diagram of X OR gate and also write down its truth table. OR Write down the truth table of exclusive OR gate.
When does light behave as a wave? When does it behave as a particle?
Define binding energy and give its formula. OR What is mass defect and binding energy? OR Who suggested that energy is radiated or absorbed in discrete packets? OR What is Mass Defect and Binding Energy of a nucleus? Write down their mathematical expressions. OR What is inductor? Determine energy stored in an inductor. OR According experimental results of Lummer and Pringshein’s what is relation in energy and temperature? OR What is solar energy? How sunlight can be converted into electrical energy? OR A beam of red light and a beam of blue light have exactly the same energy. Which beam contains the greater number of photons? Explain.
What is torsion constant? OR Define dielectric constant. Give its mathematical form. OR Define time constant and give its formula. OR What is the value of Stephen’s constant?
What is a phantom bar magnet?
How can we improve the efficiency of a transformer? OR Write the equation of efficiency of an ideal transformer. OR Why is the core of transformer laminated?
Whether time is an absolute quantity according to special theory of relativity? OR If the speed of Light were infinite, what would the equations of special theory of Relativity reduce to? OR Distinguish between general theory of relativity and special theory of relativity.
Can pair production take place in vacuum? Explain.
What is meant by line spectrum? How it can be used for the identification of elements? OR What is meant by a line spectrum? Explain, how line spectrum can be used for the identification of elements? OR How the characteristic X-rays appear on a continuous spectrum?
Show the E and — have the same units. OR Define unit of capacitance. Give its units.
What is Curie temperature? Explain it with an example. OR Define Curie’s temperature.
Differentiate between elastic deformation and plastic deformation.
Find the de-Broglei wavelength of a proton moving at a speed of 40 m/sec.
What are Hadrons and Leptons? Explain with examples. OR Differentiate between Hadrons and Leptons.
What is the main reason for the world wide use of A.C.? OR Write a note on Phase of A.C. OR Name the device which will permit the flow A.C. but oppose the flow of D.C. OR A.C. has rms value of 10A. What is its peak value?
Explain modulation? OR What do you mean by amplitude modulation?
Define modulus of elasticity and write its unit. OR Define modulus elasticity. OR Define elasticity and plasticity.
Why are heavy nuclei unstable?
Describe the force or forces on a positive point charge when placed between parallel plates: (a) With similar and equal charges (b) With opposite and equal charges.
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? OR Why is E zero inside a charged rubber balloon where charge is distributed uniformly over its surface?
What is the effect of forward biasing and reverse biasing on the width of depletion region?
Why do not we observe a Compton effect with visible light?
Define half life of an element with example.
Define electric force and electrostatics.
Define self inductance. OR Name the factors upon which the self-inductance depends.
What is meant by stimulatedemissions?
Write the names of basic forces of nature.
What are x-rays? OR What are x-rays? Give some properties of x-rays.
Do electrons tend to go to region of high potential or of low potential? Explain. OR Is electron volt unit of potential difference or energy? Explain. OR What is the electric potential at a certain point? OR What is excitation potential? OR Two equal charges are placed at some distance ’d’ apart. Find electric potential at the midpoint on a line joining these charges when: a. both has the similar charge. OR The potential is constant through a given region of space. Is the electric field zero or non zero in the region? Explain. OR Suppose that you follow an electric field line due to a positive point charge. Do the Electric field and the Potential increase or decrease? OR Is electron volt unit of potential difference or energy? Explain. OR How is a rheostat used as potential divider? OR Explain stopping potential?
Describe a circuit which will give a continuously varying potential. OR Write some important properties of a series resonance circuit. OR What are biasing requirements of a transistor for normal operation? Draw a common emitter amplifier circuit fulfilling these requirements. OR Does the induced current depend on the resistance of the circuit? OR Describe briefly the function of Photodiode by circuit diagram. OR Define R-C series circuit. OR Define RI Jseries circuit. OR A circuit contains an iron-cored inductor a switch and D C source arranged in series. The switch is closed and after an interval reopened. Explain why a spark Jumps. OR Define impedance of a circuit and give its unit. OR What is choke coil and why is it used in A.C. circuits? OR What is a transistor? How NPN transistor circuit is drawn in a common-emitter configuration? OR In a R — L circuit will the current lag or lead the voltage? OR What is resonance condition in RLC series circuit? OR A circuit contains an iron cored inductor, a switch and a D.C. source arranged in series. The switch is closed and after an interval re-opened. Explain why a spark jump across the switch contacts. OR What is wheatstone bridge? Sketch its circuit diagram. OR Define Kirchhoff’s rules of circuit analysis. OR Does the induced emf always act to decrease the magnetic flux through a circuit? OR Does the induced emf in a circuit depend on the resistance of the circuit? Explain. OR What are biasing requirements of a transistor for normal operation? Draw a common emitter amplifier circuit fulfilling these requirements.
Define absolute potential and potential gradient. OR A tungsten target is struck by electrons that have been accelerated from rest through 40 kV potential differences. Find the shortest wavelength of the bremsstrahlung. OR What is a potential barrier? What is the value of potential barrier of Si and Ge? OR What is potential at the mid point of line joining two opposite equal charges?
On which factors does electric flux depend upon. OR Define electric flux and give its unit. OR Define magnetic flux and magnetic flux density. OR Write two methods to change flux for electromagnetic induction.
A heavy nucleus becomes stable. Why? OR A heavy nucleus becomes unstable. Why?
Define unit cell and give the number of basic crystal systems.
How does stimulated emission differ from spontaneous emission?
Giwe two uses of potentiometer.
What do you mean by Dead time of a Geiger counter?
Do any of Bohr assumptions contradict classical physics?
Find the mass m of a moving object with speed 0.8 c. OR Define charge number and mass number.
What is meant by Hystersis loop?
Name two different effects of current. OR Name device that will: (a) permit flow of direct current and opposes flow of alternating current. (b) Permit flow of alternating current but not the direct current. OR Advantage of torque in a current carrying coil?
What is solenoid? OR Why is B nonzero outside a solenoid?
What is CAT-SCANNER?
Derive the dimensions of pressure and density.
Can a vector have a component greater than vector’s magnitude?
Define impulse. How is it related to linear moinentum?
Why is a cavity radiator considered as a black body?
What is coactivity of a material?
What features do longitudinal waves have common with transverse waves?
How are beats useful in turning a musical instrument?
What do you understand by the term viscosity? Give its SI unit.
What is meant by moment of inertia? Explain its significance.
Define dielectric? OR A charge particle is placed in an electric field. What is the force on the particle if the charge on the particle is doubled? OR What are the properties of electric field lines?
Define electrolysis? OR Explain the process of electrolysis and electroplating?