PHYSICS (861)

1 PHYSICS (861). CLASS XII. There will be two papers in the subject: Paper I: Theory - 3 hours .. 70 marks Paper II: Practical - 3 hours .. 15 marks Project Work .. 10 marks Practical File .. 5 marks PAPER I- THEORY: 70 Marks There will be no overall choice in the paper. Candidates will be required to answer all questions. Internal choice will be available in two questions of 2 marks each, two questions of 3 marks each and all the three questions of 5 marks each. S. NO. UNIT TOTAL WEIGHTAGE. 1. Electrostatics 14 Marks 2. Current Electricity 3. Magnetic Effects of Current and Magnetism 16 Marks 4.

2 Electromagnetic Induction and Alternating Currents 5. Electromagnetic Waves 6. Optics 20 Marks 7. Dual Nature of Radiation and Matter 13 Marks 8. Atoms and Nuclei 9. Electronic Devices 7 Marks TOTAL 70 Marks 1.. PAPER I -THEORY- 70 Marks electric field E experiences an electric . Note: (i) Unless otherwise specified, only S. I. force FE = qE . Intensity due to a Units are to be used while teaching and learning, continuous distribution of charge as well as for answering questions. linear, surface and volume. (ii) All physical quantities to be defined as and (c) Electric lines of force: A convenient when they are introduced along with their units and way to visualize the electric field.

3 Dimensions. properties of lines of force; examples (iii) Numerical problems are included from all of the lines of force due to (i) an topics except where they are specifically excluded isolated point charge (+ve and - ve);. or where only qualitative treatment is required. (ii) dipole, (iii) two similar charges at a small distance;(iv) uniform field 1. Electrostatics between two oppositely charged parallel plates. (i) Electric Charges and Fields (d) Electric dipole and dipole moment;. Electric charges; conservation and . derivation of the E at a point, (1) on quantisation of charge, Coulomb's law; the axis (end on position) (2) on the superposition principle and continuous perpendicular bisector (equatorial charge distribution.)

4 Broad side on position) of a dipole, Electric field, electric field due to a point also for r>> 2l (short dipole); dipole in charge, electric field lines, electric dipole, a uniform electric field; net force zero, electric field due to a dipole, torque on a torque on an electric dipole: dipole in uniform electric field.. = p E and its derivation. Electric flux, Gauss's theorem in Electrostatics and its applications to find (e) Gauss' theorem: the flux of a vector . field due to infinitely long straight wire, field; Q=vA for velocity vector v A, uniformly charged infinite plane sheet.

5 (a) Coulomb's law, unit of A is area vector. Similarly, for electric . charge; permittivity of free space field E , electric flux E = EA for E A. and of dielectric medium.. Frictional electricity, electric charges and E= E A for uniform E . For . (two types); repulsion and non-uniform field E = d = . attraction; simple atomic structure - Special cases for = 00, 900 and 1800. electrons and ions; conductors Gauss' theorem, statement: E =q/ 0. and insulators; quantization and q conservation of electric charge; or E = dA = 0 where E is for E. Coulomb's law in vector form.

6 (position coordinates r 1 , r 2 not a closed surface; q is the net charge necessary). Comparison with Newton's enclosed, o is the permittivity of free law of gravitation; space. Essential properties of a Superposition principle Gaussian surface.. ( F= 1 ). F 12 + F 13 + F 14 + . Applications: Obtain expression for E.. due to (1) an infinite line of charge, (2). (b) Concept of electric field and its a uniformly charged infinite plane thin intensity; examples of different fields; sheet. gravitational, electric and magnetic;. Electric field due to a point charge (ii) Electrostatic Potential, Potential Energy and Capacitance E = F / qo (q 0 is a test charge); E for a group of charges (superposition Electric potential, potential difference, principle); a point charge q in an electric potential due to a point charge, a dipole and system of charges.

7 2. equipotential surfaces, electrical potential 1 2 1 1 Q2. energy of a system of two point charges CV = QV = ) and energy and of electric dipole in an electrostatic 2 2 2 C. field. density. Conductors and insulators, free charges (c) Dielectric constant K = C'/C; this is also and bound charges inside a conductor. called relative permittivity K = r =. Dielectrics and electric polarisation, / o; elementary ideas of polarization of capacitors and capacitance, combination matter in a uniform electric field of capacitors in series and in parallel. qualitative discussion; induced surface Capacitance of a parallel plate capacitor, charges weaken the original field; results.

8 Energy stored in a capacitor. in reduction in E and hence, in pd, (V);. (a) Concept of potential, potential for charge remaining the same Q = CV. difference and potential energy. = C' V' = K. CV'; V' = V/K;. Equipotential surface and its and E = E ; if the Capacitor is kept properties. Obtain an expression for K. electric potential at a point due to a connected with the source of emf, V is point charge; graphical variation of E kept constant V = Q/C = Q'/C' ; Q'=C'V. and V vs r, VP=W/q0; hence VA -VB = = K. CV= K. Q. WBA/ q0 (taking q0 from B to A) = increases; For a parallel plate capacitor (q/4 0)(1/rA - 1/rB); derive this with a dielectric in between, equation; also VA = q/4 0.

9 1/rA ; for C' = KC = K. o . A/d = r . o .A/d. q>0, VA>0 and for q<0, VA < 0. For a 0 A. Then C = ; for a capacitor collection of charges V = algebraic d . sum of the potentials due to each . r . charge; potential due to a dipole on its partially filled dielectric, capacitance, axial line and equatorial line; also at C' = oA/(d-t + t/ r). any point for r>>2l (short dipole). Potential energy of a point charge (q) 2. Current Electricity . in an electric field E , placed at a point Mechanism of flow of current in conductors. P where potential is V, is given by U.

10 Mobility, drift velocity and its relation with =qV and U =q (VA-VB) . The electric current; Ohm's law and its proof, electrostatic potential energy of a resistance and resistivity and their relation to system of two charges = work done drift velocity of electrons; V-I characteristics W21=W12 in assembling the system; U12 (linear and non-linear), electrical energy and or U21 = (1/4 0 ) q1q2/r12. For a power, electrical resistivity and system of 3 charges U123 = U12 + U13 + conductivity. Temperature dependence of 1 q1 q 2 q1 q3 q 2 q3 resistance and resistivity.