W13 III 04 1000 Time: 2% Hours Seat No. I I I I I I Physics Subject Code [iliili] Paper Code ~ Total No. of Questions: 5 (Printed Pages: 14) Maximum Marks: 55 INSTRUCTIONS: (i) All questions are compulsory (ii) Answers to the Multiple Choice Questions should be written by choosing and writing the correct alternative. (iu) There is no overall choice. However internal choice has (iv) (v) been provided in two q~estions offour marks each, and one question of three marks. Use of ca\culators is not permitted. However, you may ask for mathematical tables. You may use the following values of physical constants wherever necessary : Constants : c = 3 x 108 ms-l e = 1.6 x 10-19 C h = 6.6 x 10-34 Js me = 9.1 x 10--31 kg 110= 4n x 10-7 TmA-l..-!.- = 9 x 109 Nm2C-2 4n o H-702(OO9) Energy of ground state of H atom =-13.6 ev. 0 [Conld...
1. (A) The ratio of diameters of two wires made of the same material and having the same length is 1 2. The ratio of their electrical resistivities is. 1 : 2..J2. 1 : 1. 4 (B) The force of attraction between two point charges placed a distance 'd' apart is F. What distance apart should they be kept 'in the same medium, so that.the force between them.is!? 3. (C) Name the constituent radiation of the electromagnetic spectrum which: 2 (i) is emitted during the decay of a radioactive nuclei. (ii) is used in satellite communication. (Ui) is absorbed from sunlight by the Ozone layer. (iv) maintains the average temperature of the earth through the greenhouse effect. CD [Contd...
(D) For the following circuit, find the value of 'I' in ampere unit 2 6o.JL ~A.~- ~ 10V\- (E) Using Gauss's law, derive an expression for the electric field at a point near an infinite, uniformly charged plane sheet. 2 (F) Two cells of emfs "1 and "2 and internal resistances rl and r2 are connected in parallel by joining their like terminals together across points Bl and B2' E, A~:r, 4' B, b. BL C I~"'" ~ -,('>-. Obtain an expression for the equivalent emf of the above combination of cells. CD [Contd...
How will the above expression change, if the unlike terminals of 1 and 2 are connected together in parallel as shown below?.. h-,(~ E... 2. (A) The figure shows a distribntion of charges at the four comers of a rectaugle. At the point P, :5~B ~ D C -5~C + 5~C. both resultant field and potential are positive.. both resultant field and potential are zero.. the resultant field is negative but resultant potential is positive.. the resultant field is positivebut resultant potential is negative. 0 [Contd...
(B) The electric field at a distance 2 from the centre of a charged 3R conduding spherical shell of radius R, is E. How much will the R field be at a distance 2 from the centre of the shell? (C) Two lines A and B show the variation of the de Broglie wavelength 1 A with N' where V is the accelerating potential difference for two particles carrying the same charge. Which one of the two represents the particle of smaller mass? Justify your answer. 2 r / ;. ' /.. V~~/A 0) 1/ JV (D) In Young's double slit experiment the slits are 0.5 mm apart and interference is observed on a screen placed at a distance of 100 em from the slits. It is found that the 9th brigbt fringe is at a distance of 9.0 rum from the second dark fringe. Calculate the wavelength of light used. 2 CD [Contd...
(E) Derive Sne]]'s law of refraction by drawing the refracted wavefrant corresponding to a plane wavefront incident on the boundary separating a rarer medium from a denser medium. (F) In the given arrangement of capacitors, each 3 ~F capacitor has got 6 x 10-4,J of energy. Determine tlie potential difference across the 2 ~F capacitor and the total energy stored in the circuit. 3A'H~I~ 7~H'~1 +~. V Or An electric dipole of length 10 em having charges ",6 x 10-3 C, placed at 300 with a uniform electric field E, experiences a torque of magnitude 613 N-m. Calculate (i) the electric dipole moment of the dipole, (ii) the magnitude of the electric field E, and (iii) the potential energy of the dipole. H.702 (009) CD [Contd...
3. IA) When a ray of light enters a denser medium. its velocity increases. its wavelength decreases. it may sufler a total internal reflection. its frequency increases (B) A girl looking at a person wearing a shirt with a pattern comprising of vertical and horizontal lines is able to see the vertical lines correctly but the horizontal ones distorted. What is the defect of vision called? How is such a defect corrected? 1 (C) An armature coil consists of 20 turns of wire, each of area 0.1 m2 and total resistance of 25.0 Q. It rotates in a magnetic field of 0.5 T at a constant frequency of 150 Hz. Calculate the value n of : (i) maximum induced emf prod need in the coil. (ii) average induced emf produced in the coil. (2) [Contd...
(D) A bar magnet of magnetic moment 1.5 Jff lies aligned with the direction of a uniform magnetic field of 0.22 T. (i) What is the amount of work done by an external torque to turn the magnet so as to align its magnetic moment:. (n) normal to the field direction? (b) opposite to the field direction? (ii) What is the magnitude of the torque acting on the magnet in the cases (n) and (b) stated above? (E) With the help of a neat ray diagram and graph showing the variation of angle of deviation with the angle of incidence, derive an expression for the refractive index of the material of a prism. Hence derive the expression for the angle of minimum deviation of a thin prism. 4 Or Obtain the relation between object distance, image distance and the focal length for a concave mirror. Draw the necessary ray diagram. Derive the linear magnification formula for the image formed by the concave mirror. 4 (8) [Contd...
4. (A) A wriform electric field and a uniform magnetic field exists in a region in the same direction. An electron is projected with a velocity pointed in the same direction as that of the two fields. The electron will :. not be deflected but its speed will increase. be deflected with increase in speed. be deflected with decrease in speed. not be deflected but its speed will decrease (B) A resistor of 10 Q and a capacitor having a reactance of 5 Q are in series across a d.c. source. What will be the impedance of this circuit? (C) Four nuclei of an element fuse together to form a heavier nucleus. If the process is accompanied by the release of energy, which of the two, the parent or the daughter nucleus would have a higher binding energy per nucleon? Why? CD [Contd...
A radioactive nucleus D decays according to the following sequence: D~Dl ~D2 ~D3 ~D4' If the mass number and atomic number for D4 are respectively 172 aod 69, then find the corresponding values for D. 2 (D) An a.c. voltage V = Vm sin OJtis applied across a pure inductor of inductance L. Show mathematically that the current flowing through it lags behind the applied voltage by a phase angle of %.. An inductor L of reactance XL is connected in series with a bulb B to an a.c. source. How will the brightness of the bulb change when: (i) number of turns of the inductor is reduced and (ii) a capacitor of reactance Xc =XL is included in series in the same circuit? (E) Two infinitely long conductors canying currents in the same direction are placed parallel to each other. Derive the expression for the force per unit length experienced by each conductor. Hence define one ampere. [Contd... @
If the direction of the current io one. of the conductors is reversed, what will be the change in the force experienced by the two conductors? 4 Or For a moviog coil galvanometer, show that the current passiog through the coil is directly proportional to the deflection of the coil. A galvanometer cannot be used directly to measure the value of the current io a given circuit. Why? What modification has to be made io.a galvanometer, so that it can be used as an ammeter? 4 5. (A) In Bohr's model of H atom, the ratio of kidetic to the total energy of the electron io the nth quantum state is :. +1. -2. +2. -1 @ [Coutd...
(B) A pure semiconductor has equal electron and hole concentrations. On doping with a certain impurity, the hole concentratiou increases (i) What is the type of extrinsic semiconductor obtained on doping? (ii) How does the energy gap vary with doping? (C) A and B are the inpnts given to the logic cireuit shown below. IdentifY (;he logic operation performed by this circuit. 2 A=V-Q>- B y The following figure shows the variation of one of the input A and the output Y obtsined for the above logic circuit. Mention the time intervals for which the input B has to be low, so as to obtsin the variation of Y as shown below- Ii 'j t. I -t"2.- 1:, 'i t:,,- -t,;, -1.7 -tg @ [Conld...
(D) Explain giving any two reasons, why modulation of a signal is required before transmission in a communication system. 2 (E) The following figure shows the trajectories of a particles in the coloumb field of a target nucleus. In the figure, what does '6' represent '! For what values of e, will '6' be (i) maximum (ii) minimum. 2 1:.. b 'f 0 :---,. Target nucleus!-70?ro091 (13) [Contd...
(F) An a.c. signal is fed to two circuits X aud Y aud the correspouding output in the two cases have the wavefonns as shown below. Name the circuits X and Y. Also draw their detailed circnit diagrams. Which of the two cireuits is more efficient and. why? r'\f\.i\.; ill h' f\ 1\, / -7m7