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PHYSICS II PUC IMPORTANT QUESTIONS THREE OR FIVE MARKS QUESTIONS:Chapter 1 – Electric charges & fields 1) 2) 3) 4) 5) Mention the properties of electric charges. State and explain coulomb’s law in Electrostatics. Derive the expression for electric field at a point on the axis of the dipole. Obtain the expression for electric field at a point on the equatorial line of the dipole. Deduce the expression for torque on a dipole placed in uniform electric field. When will be the torque acting on the electric dipole maximum and minimum? 6) Mention the properties of electric lines of force. 7) State and explain Gauss’s law in electrostatics. 8) Obtain the expression for electric field at a point a. Outside a charged thin spherical shell b. Just outside a charged thin spherical shell, by using Gauss law 9) Obtain an expression for electric field due to an infinitely long straight uniformly charged wire by using gauss law. 10) Obtain an expression for electric field due to uniformly charged infinite flame sheet by using gauss law Chapter 2 – Electro static potential & Capacitance 1) 2) 3) 4) 5) Derive an expression for electric potential due to an isolated point charge. Derive the relation between electric field and electric potential. Derive the expression for capacitance of parallel plate capacitor without di electric medium. Derive the expression for energy stored in a capacitor. Obtain an expression for the following a. Effective capacitance of two capacitors in series b. Effective capacitance of two capacitors in parallel 6) Draw the labeled diagram of a Van de Graaff generator. Chapter 3 – Current Electricity State & explain Ohm’s law. Write its limitations. Derive the relation between current density and conductivity of a conductor. Derive an expression for conductivity of a material in terms of relaxation time. Derive an expression for equivalent resistance a. When two resistors are in series b. When two resistors are in parallel 5) Find the expressions for the equivalent emf and equivalent internal resistance of the combination when two cells of different emfs and different internal resistances are a. Connected in series and b. Connected in parallel 1) 2) 3) 4) 6) State and explain Kirchhoff’s laws. 7) Obtain the condition for balance of a wheat stone bridge using Kirchhoff’s laws. Chapter 4 – Moving charges and Magnetism 1) Derive an expression for magnetic field strength (magnetic field intensity) at any point on the axis of a circular current loop using Biot – Savart’s law. 2) Derive an expression for magnetic field intensity due to a straight current carrying wire by applying Ampere’s circuital law. 3) Explain the construction and working of a cyclotron. 4) Derive an expression for the force expericed by a current carrying conductor placed in uniform magnetic field. 5) Derive an expression for the force between two straight parallel current carrying wires and hence define ampere. 6) Derive an expression for magnetic dipole moment of an electron revolving in the nth orbit of an atom & Bohr’s magneton. 7) What is an ammeter? Explain how a galvanometer is converted into an ammeter? 8) What is voltmeter? Explain how a galvanometer is converted into a voltmeter? Chapter 5 – Magnetism and matter 1) 2) 3) 4) Mention the properties of magnetic field lines. Show that a bar magnet is equivalent to a current carrying solenoid. Distinguish between diamagnetic and paramagnetic materials. Explain hysteresis loop. Chapter 6 – Electromagnetic Induction 1) State and explain lenz’s law. 2) Deduce an expression for the emf induced across the ends of a conducting rod moving in a perpendicular magnetic field. 3) Derive an expression for energy stored in an inductor. 4) Give the theory of AC generator. Chapter 7 – Alternating current 1) Derive the expressions for the instantaneous current in an ac circuit with a a. Pure resistor b. Pure inductor c. Pure capacitor Draw the phasor diagrams and mention the phase relation between current and voltage in each case. 2) Derive expressions for resultant voltage impedance, current and phase angle in series LCR circuit using phasor diagram. 3) Mention the formula for current in series LCR circuit & hence mention the condition for resonance. 4) Obtain the expression for resonant frequency. 5) Write a note on transformer. Chapter 9 – Ray Optics and optical instruments 1) Write the Cartesian sign conventions used in the mirrors. 2) 3) 4) 5) Derive the relation between focal length and the radius of curvature of a mirror. Derive mirror equation in the care of a concave mirror producing real image. Write a short note on TIR. Derive the expression Where the symbols have the usual meaning. 6) Give reasons for the following: a. Blue colour of the sky b. Sun appears reddish during sunrise and sunset 7) Derive the relation connecting R.I, object distance, image distance and radius of curvature for refraction at a spherical surface. 8) Derive lens makers formula. 9) Derive an expression for equivalent focal length of two thin convex lenses in contact. 10) Draw the ray diagrams for the following and mention the expression for magnification a. Image formation at least distance of distinct vision in case of simple microscope b. Image formation at infinity in the case of simple microscope c. Image formation at least distance of distinct vision in the compound microscope d. Image formation at least distance of distinct vision in an astronomical telescope e. Reflecting telescope Chapter 10 – Wave optics 1) Derive the law of reflection of light on the basis of Huygen’s wave theory of light. 2) Derive the law of refraction (Shell’s law) on the basis of Huygen’s wave theory of light when the light travels from rarer medium to denser medium. 3) Give the theory of interference. Or Arrive at the conditions for constructive and destructive interference. 4) Describe Young’s double shit experiment to demonstrate interference of light. 5) Obtain an expression for interference fringe width in Young’s double slit experiment. 6) Explain the Fraunhoffer diffraction through a single slit. 7) Distinguish between interference and diffraction. 8) Write a note on Polaroids. 9) State and prove Brewster’s Law of polarization. Chapter 11 – Dual Nature of Radiation & Matter 1) Write the experimental observations of photoelectric effect or Laws of Photo electric effect. 2) Outline the Einstein’s explanation of photoelectric effect. 3) Mention the properties of a photon. Chapter 12 – Atoms 1) Explain Geiger – Marsden experiment OR Explain Rutherford’s experiment. 2) Obtain an expression for the energy of an electron in hydrogen atom in terms of radius using Rutherford model of an atom. 3) Write the postulates of Bohr’s Atomic model. 4) Obtain an expression for the radius of nth Bohr orbit of hydrogen atom using Bohr’s postulates. 5) Obtain an expression for the energy in the nth Bohr orbit of the hydrogen atom by assuming the expression for radius. 6) Using Balmer’s formula, write the empirical formulae for wave number of different series of spectral lines of hydrogen atom. 7) Write the energy level diagram for hydrogen atom indicating different series of spectral lines. 8) What are the limitations of Bohr’s theory? Chapter 13 – Nuclei 1) 2) 3) 4) 5) 6) Write the properties of nucleus. What are the characteristics of nuclear forces? What is specific binding energy? Explain the features of Binding energy curve. Write the differences between nuclear fission and fusion. State and explain Radioactive decay law. Derive N = N0 Or Derive an expression for the number of atoms present in a radioactive substance in a given instant of time Or Show that radioactive decay is exponential. 7) Define half life of a radioactive element and obtain the expression for half life. Chapter 14 - Semi conductor Electronics 1) 2) 3) 4) 5) 6) 7) 8) 9) Distinguish between intrinsic and extrinsic semiconductor. Distinguish between n-type and p-type semi conductors. Explain the formation of p-n junction. Explain the working of p-n junction in the forward and reverse bias. Draw the characteristic curves. With a circuit diagram, explain the working of p-n junction as half wave rectifier. Draw input and output waveform. With a circuit diagram, explain the working of p-n junction as full wave rectifier. Draw input and output wave forms. Explain the working of Zener diode as a voltage regulator. Distinguish between n-p-n and p-n-p transistor. Explain the working of npn transistor in CE mode as an amplifier. Draw input and output wave forms. Obtain the expression for voltage gain.