## Physics Long 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.

# موسٹ امپورٹنٹ سوالات کے لیا سائٹ پیپر سے کچھ دن پھیلے بی چیک کریں: شکریہ

یہ پیپر اولڈ اور نیو کورس کا تجزیہ کر کے تیار کیا گیا ہے (٢٠١٢ سے ٢٠١۶ اولڈ پپیرس ). اپپنے سلیبس کے مطابق تیاری کریں شکریہ.

## Frequently Asked Questions (2012 to 2016)

**Physics Important Long Questions Variations**

What is radioactive? Discuss emission of a, ß and ? particles from radioactive nuclei. OR What do you meant by radioactivity? Also define radiation types?

A 75 kg person receives a whole body radiation dose of 24 m-rad, delivered by a-particles for which RBE factor is 12. Calculate the absorbed energy in joules. OR What do you know about the biological effect of radiation? Write in detail.

Find relation for strain energy in deform materials. OR What is the meant by strain energy? Derive the relation for strain energy in a deformed material from the area under the force extension graph.

What is C.R.O.? Describe its contraction and working point out its uses in electronics

What are the main parts of A.C. generator? Describe its principle and working. Also derive the equation of emf induced in its coils.

Define electron volt and find its relation with joule.

What is Compton Effect? How was this phenomenon explained by A.H. Compton on the basis of the particle theory of light? OR What is Compton Effect calculate Compton wavelength. What does it indicate about nature of light?

What is Wheatstone bridge? Describe its construction and working.

What is frame of reference? Explain with examples. Differentiate inertial and none—inertial frames of reference.

How Milikan’s method can be used to determine the charge on an electron?

Define Lorentz force. Discuss the determination of —e of an electron.

Differentiate between an A.C. and D.C. currents.

Differentiate between forward biasing and reverse biasing of a p-n junction.

Differentiate between N-type and P-type substances.

Differentiate between Young’s Modulus E and Bulk Modulus K.

Differentiate between baryons and mesons.

Differentiate critical temperature from Curie temperature.

Find charge on electron by Millikan’s method.

A rectangular bar of iron is 2 cm by 2 cm in cross-section and 40 cm long. Calculate its resistance id resistivity of iron is 11 x 10-8 O-m

Define galvanometer. How it can be converted into ammeter and voltmeter? Describe them. OR What shunt resistance must be connected across a galvanometer of 50.0? resistance which gives full scale deflection with 2.0 m A current, so as to convert it into an ammeter of range 10.0A? OR Describe the principle, construction and working of moving coil galvanometer.

An ideal step down transformer is connected to main supply of 240 V. It is desired to operate a 12V, 0 W lamp. Find the current in the primary and the transformation ratio.

Explain paramagnetic, diamagnetic and ferromagnetic substances.

What is the resonant frequency of a circuit which includes a coil of inductance 2.5 H and a capacitance of 40 µ F? OR Two coils are placed side by side. An emf of 0.8 V is observed in one coil when the current is changing at the rate of 200 AS- in the other coil. What is the mutual inductance of the coil? OR Find the capacitance required to construct resonance circuit of frequency 1000 KHZ with an inductance of mH.

Find energy stored in the inductor. OR What is an inductor? Determine energy stored in an inductor. OR Find the capacitance required to construct a resonance circuit of frequency 1000 KHz with an inductor of 5mH.

Define impedance of a circuit. OR Define impedance. Find its value for R.C series circuit and explain with phase or diagram. OR What is R-C series circuit? Calculate the impedance and phase angle of R-C series circuit? OR Derive the expression for impedance and phase angle for R – C and R – L series circuit when excited by a.c. supply.

A 1.2 cm diameter cylinder is subjected to a load of 200 kg. Calculate the stress on the bar in mega Pascal. OR 1.25 cm diameter cylinder is subjected to a load of 2500 kg. Calculate the stress on the bar.

Explain use of diode as full NA a v e rectifier. OR What is meant by redifications? Explain the action of a semi-conductor diode as half wave rectifier. OR What is semi-contactor diode? Explain its behavior when it is forward biased and reversed biased. OR What is semi-contactor diode? Explain its characteristics during forward and reversed biased.

Explain mass defect and binding energy. OR Find the mass defect and binding energy for tritium, if atomic mass of tritium is 3.016049 U. Mass of proton = 1.007276 U, mass of neutron = 1.008665 U. OR Discuss mass defect and binding energy and explain the stability of nuclei on the basis of binding energy.

Find the wavelength of the spectral line corresponding to to the transition in hydrogen from n = 6 state to n = 3 state. OR Give the postulates of Bohr’s model of a hydrogen atom and drive the quantized radii of hydrogen atom. OR In Bohr’s atomic model of hydrogen atom, the electron is in an orbit around the nuclear proton at a distance of 5.29 x 10-11 m with a speed of 2.18 x 106 m/s. Find (i) Electron potential that a proton exerts at this distance. (ii) The ionization energy for the atom is eV.

Define capacitor. Find an expression for the capacitance of a parallel plate capacitor. OR Derive an expression for energy stored in a changes capacitor. Also calculate the energy stored in an electric field. OR Find the value of the current flowing through a capacitor 0.5 µF when connected to a source of 150 V at 50 Hz. OR A 100 uF capacitor is connected to an alternating voltage of 24V and frequency 0 Hz. Calculate: (i) reactance of a capacitor (ii) current in the circuit. OR Describe A.C. through a capacitive circuit and find the relation for the reactance of capacitor. OR Find the value of the current flowing through a capacitor 0. p.F when connected to a source of 10 V at 0 Hz.

Find force on a moving charge in magnetic field. OR Find an expression for the torque acting on a current carrying coil place in a magnetic field. OR State Ampere’s law. Calculate the magnetic field due to current flowing in a solenoid. OR State and explain Lenz’s law. How this law explains conservation of energy during electromagnetic induction? OR Distinguish between magnetic flux and flux density. OR Explain the principle of generation, transmission and reception of electromagnetic waves with an example. OR Describe the motion of an electron in uniform magnetic field and derive its expression of e/m.

Derive an expression for the force on a charge particle moving in the magnetic field. OR State Ampere’s law and find relation for magnetic field due to current carrying solenoid. OR An electron is placed in a box about the size of an atom that is about 1.0 x 10-10m. What is the velocity of the electron? OR A square coil of side 16 cm has 200 turns and rotates in a uniform magnetic field of magnitude 0.0 T. if the peak value of e.m.f is 12V, %% fiat is angular velocity of coil? OR Alpha particles ranging in speed from 1000 mS-1 to 2000 mS-1 enter a velocity selector where the electric intensity is 300 Vm-1 and the magnetic induction is 0.20 T. Which particle will move undeviated?

A D.C motor operates at 240 volts and has a resistance of 0.5 O. When the motor is running at normal speed, the armature current is 15 A. find back emf in the armature.

Describe the formation of energy bands in solids. OR Distinguish between crystalline and polymeric solids. OR Describe the formation of energy bands in solids. Explain the difference amongst electrical behavior of conductors, insulators and semi-conductor in term of energy band theory. OR Explain the difference amongst electrical behaviour af conductors, insulators and semi-conductors in terms of energy band theory.

What is the de-Broglie wavelength of an electron whose K.E. is 120 eV? OR Give the experimental proof of de-Broglie hypothesis. OR A particle of mass 5.0 mg moves with speed of 8.0 mS-I. Calculate its de-Broglie wavelength. (h = 6.63 x 10-34 J.S.)

What is potentiometer? Describe its principle, construction and working. OR What is potentiometer? How it can be used as;(i) potential divider (ii) measuring of emf of a cell?

What is C.R.0.? Describe its construction and working. Point out its uses in electronics.

Explain RLC series circuit in detail. Also point out its important properties. OR Describe RLC series circuit. Derive relation for resonance frequency. Also give any four properties of series resonance.

What is an amplifier? Explain the CE transistor as an amplifier. Determine the voltage gain of transistor amplifier also. OR Draw the circuit diagram of non-inverting amplifier and label it. Evaluate a relation for its gain. OR How an n-p-n transistor works as an amplifier? Give its circuit diagram. Deduce the relation for its voltage gain. OR What is transistor and how is it used as an amplifier? Give its circuit diagram. Deduce the relation for its voltage gain. OR What is operational amplifier? Derive relation for the gain of non-inverting op.amplifier.

What is the energy of photon in a beam of infrared radiation of wavelength 1240 nm? OR What is the difference between excitation of an atom by (a) a photon (b) an electron.

What are X-rays? How these are produced? Write down any two uses of X-rays. OR Explain how x-rays are produced? Write any one use of x-rays. OR Explain inner shell transitions and X-rays production. OR Explain characteristics X-ray and continuous X-ray spectra. Also write two uses of X-ray.

State and explain Coulomb’s law for electrostatic charges. Give its vector form also. OR Define Gauss’s law and find electric intensity due to infinite sheet of charge by using Gauss’s law. OR Give the statement of Ampere’s law. Apply it to find B due to a current carrying solenoid. OR State Gauss’s law and find electric intensity due to an infinite sheet of charge. OR State Gauss’s Law. Find the electric flux through a closed surface enclosing a point change. OR State Ampere’s law and derive the relation B = p.o n1 for solenoid. OR Radiation from a point obeys the inverse square law. If the count rate at a distance of 1.0 m from Geiger counter is 60 counts per minute, what will be its count rate at .0 m from the source?

What is electric field? Find the electric field intensity due to an infinite sheet of charge. OR How many electrons pass through an electric bulb in one minute if 300 A current is passing through it? OR Define photoelectric effect. Explain photoelectric effect on the basis of quantum theory. OR Explain photoelectric effect on the basis of Einstein’s quantum theory. Also derive Einstein equation. OR Difference between electric and gravitational forces.

What is doping? Describe the formation of N-type and P-type semi-conductors.

What are black body radiations? Explain the effect of temp. on radiation emitted by hot body. Also discuss energy distribution curve of black body among different

wavelength. OR What is G.M. Counter? Give its construction. How is it used to count the nuclear radiations?

What is LASER? Explain its principle and LASER Action in full details.

What are isotopes? Describe Aston mass spectrograph. How can it be used for detection of isotopes? OR How isotopes are detected with a mass spectrograph? OR If 292U decays twice by a-emission, what is the resulting isotope?

What is the energy difference between the two levels from which this transition results?

Define extrinsic and intrinsic semi conductors. How can we obtain P-type and N-type substances? OR Difference between intrinsic and extrinsic semi conductors OR Explain contactor insulators and semiconductors on the bases of energy band theory. OR What are semi-conductors? How P-Sype and N-type materials are formed?

Explain R-L-C series resonance circuit and give its properties. OR Discuss R-L-C series circuit in detail and find an expression for resonance frequency.

Compute the shortest wavelength radiation in the Balmer series. What value of n must be used? OR Comptite the shortest wavelength radiation in the Balmer series.

Explain Heisenberg Uncertainty Principle. OR State and prove the Heisenberg Uncertainty Principle.

Write a note on electric potential at a point due to point charge. OR A particle having a charge of 20 electrons on it falls through a potential difference of 100 volts. Calculate the energy acquired by it in electron volt. OR What is the difference between electrical potential energy and electric potential at any point of an electric field? OR Write a note on electric potential at a point due to point charge. OR Do electrons tend to go to region of high potential or lower potential? OR What is electric potential? Derive an expression of electric potential at a point due to a point charge. OR Electron in an X-ray tube are accelerated through a potential difference of 3000 V. if these electrons were slowed down in a target, what will be the minimum wavelength of X-ray produced? OR A tungsten target is struck by electron that gas been accelerated from rest through 40 KV potential difference. Find the shortest wavelength of the bremsstrahlung radiation emitted. OR A particle carrying a charge of “2e” falls through a potential difference of 3.0 volts. Calculate the energy acquired by it. OR An electron is accelerated through a potential difference of 50 volts. Calculate its de-Broglie wavelength. OR Define absolute potential and derive an expression for the electrical potential at a certain point due to a point charge. OR The electronic flash attachment for a camera contains, a capacitor for storing the energy used to produce the flash. In one such unit, the potential difference between the plates of a 70 uF capacitor is 0V. Determine the energy that is used to produce the flash. OR What is electric potential? Find the electric potential at a point due to a point charge. OR The potential difference between the terminals of a battery in open circuit is 2.2 volts. When it is connected across a resistance of ohm, the potential falls to 1.8 volts. Calculate the current and internal resistance of the battery. OR An electron is accelerated through a potential difference of 0 volts. Calculate its de-Broglie wavelength.

Define motional e.m.f and derive a relation for it.

Find the value of the current flowing through a capacitance 0.5 µF when connected to a source of 150 V at 50 Hz

The current flowing into the base of a transistor is 100 µ A. Find the collector current Ic its emitter current IE, if the value of current gain ß is 100.

Write Bohr’s second postulate and find out formula for Bohr’s quantized radii.

Define resistivity and explain its dependence upon temperature. Also derive a relation for temperature co-efficient in term of resistivity. OR What is temperature co-efficient of resistance and resistivity? Derive the equations. OR What is resistivity and conductivity? Name their units. How resistivity depends upon temperature? OR What is resistivity? Explain the effect of temperature upon resistivity. OR Differentiate between resistance and resistivity?

In a certain circuit the transistor has a collector current of 10 m A and a base current of 40 µ A. What is the current gain of the transistor? OR In a certain circuit, the transistor has a collector current of 10mA and a base current of40/LA.

What is the energy in eV of quanta of wavelength 400 nm?

X –ray of wavelength 22 pm are scattered from a carbon target. The scattered radiation being viewed at 85 ° to the incident beam. What is Compton shift: (here h = 6.63 x 10-34 J.S) and (cos 85 ° = 0.087)

The half life of an isotops is 9.70 hours. Find its decay constant. OR The half life of 91/38 Sr is 9.70 hours. Find its decay constant.

What is nuclear reactor? Describe the function of its main parts.

A charge of 90 C passes through a wire in one how and 1 minutes. What is the current in the wire? OR What stress would cause a wire to increase in length by 0.01%, if the Young’s module of the wire is 12 x 1010 Pa. What force would produce this stress if the diameter of wire is 0.56mm? OR A 1.0 m long copper wire is subjected to stanching force and its length increases by 20 cm. calculate the tensile strain and percentage elongation which the wire undergoes. OR A solenoid 15 cm long has 300 turns of wire. A current of 5 A flows through it. What is the magnitude of magnetic field inside the solenoid? OR A wire 2. m long and cross-section area 10 IT12 is stretched 1. mm by a force of 100 N in the elastic region. Calculate (it the strain) Young’s modulus. OR The resistance of an iron wire at 0°C is 1 x 104 Q. What is the resistance at 00°C if the temperature coefficient of resistance of iron is .2 x 10 K-? OR Find the value of magnetic field that will cause a maximum force of 7.0 x 10- N on a 20.0 cm straight wire carrying a current of 10.0 A. OR What current should pass through a solenoid that is 0. m long with 10,000 turns of copper wire so that it will have a magnetic field of 0.4 T?

Distinguish between general theories of relativity special theory, of relativity.

Differentiate between volume stress and shear stress.

Distinguish between orbital electrons and free electrons.