
	Trending ▼ ICSE CBSE 10th ISC CBSE 12th CTET GATE UGC NET Vestibulares ResFinder

ISC Class XII Sample / Model Paper 2024 : Physics

10 pages, 0 questions, 0 questions with responses, 0 total responses,

Aditya
South City International School (SCIS), Kolkata

+Fave Message

Profile Timeline Uploads

Home > cynicbeast >

Formatting page ...

FIRST TERMINAL(2023-24), MODEL PAPER PHYSICS PAPER 1(THEORY) --------------------------------------------------------------------------------------------------Maximum Marks: 70 Time Allowed: Three Hours (Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time.) This paper is divided into four sections A, B, C and D. Answer all questions. Section A consists of one question having sub-parts of one mark each. Section B consists of seven questions of two marks each. Section C consists of nine questions of three marks each, and Section D consists of three questions of five marks each. Internal choices have been provided in two questions each in Section B, Section C and Section D. The intended marks for questions are given in brackets [ ]. All working, including rough work, should be done on the same sheet as and adjacent to the restof the answer. Answers to sub parts of the same question must be given in one place only. A list of useful physical constants is given at the end of this paper. A simple scientific calculator without a programmable memory may be used for calculations. SECTION A 14 MARKS Question 1 Page 1 of 10 (A)In questions (i) to (vii) below, choose the correct alternative (a), (b), (c) or (d) for each of the questions given below: (i) A closed surface in vacuum encloses charges -q and +3 q. The total electric flux emerging out of the surface is : [1] (a) Zero (b) 2q/ o (c) 3q/ 0 (d) 4q/ 0 (ii).A circular coil carrying a current I has radius R and number of turns N. If all the three, i.e., the current I, radius R and number of turns N are doubled, then, magnetic field at its center becomes: [1] (a) Double (b) Half (c) Four times (d) One fourth (iii) When a light wave travels from air to glass : [1] (a) its wavelength decreases (b) its wavelength increases (c) there is no change in wavelength (d) its frequency decreases. (iv)Einstein s photoelectric equation is : [1] (a) Emax = h 0 (b) Emax = hc/ 0 (c) Emax = hv 0 (d) Emax = hc/ 0 (v). Two thin lenses having optical powers of -10D and + 6D are placed in contact with each other. The focal length of the combination is : [1] (a) + 0.25 cm Page 2 of 10 (b) 0.25 cm (c) + 0.25 m (d) 0.25 m (vi) A moving electron enters a uniform and perpendicular magnetic field. Inside the magnetic field, the electron travels along : [1] (a) a straight line (b) a parabola (c) a circle (d) a hyperbola (vii) A wire of resistance R is cut into n equal parts. These parts are then connected in parallel with each other. The equivalent resistance of the combination is : (a) nR (b) R/n (c) n/R2 (d) R/n2 (B)Answer the following questions briefly: (i) Write an expression which connects current density with drift speed. [1] (ii) Calculate the net emf across A and B shown in Figure 1 below : [1] (iiii) Why are the pole pieces of a horseshoe magnet in a moving coil galvanometer made cylindrical in shape ? [1] (iv) What is the value of power factor for a pure resistor connected to an alternating current source?[ 1] Page 3 of 10 (v)State any two factors on which motional emf depends . (vi) Explain Curie s law for a para magnetic substance. [1] (vii) In a regular prism, what is the relation between angle of incidence and angle of emergence when it is in the minimum deviation position ? [1] SECTION B 14 MARKS Question 2 (i) [2] Three capacitors C1 = 3 F, C1 = 6 F and C1= 10 F are connected to a 50 V battery as shown in the Figure 1 below : Calculate : (i) The equivalent capacitance of the circuit between points A and B. (ii) The charge on C1 OR (ii) Two resistors R1 = 60 and R2 90 are connected in parallel .If electric power consumed by the resistor R1 is 15 W, calculate the power consumed by the resistor R2. Question 3 [2] Draw a labelled circuit diagram of a potentiometer to measure the internal resistance r of a cell. Write the working formula (derivation is not required). Question 4 Page 4 of 10 Figure 4 below shows a graph of emf e generated by an ac generator versus time t . [2] What is the frequency of the emf ? Question 5 (i) PQ is a long straight conductor carrying a current of 3A as shown in Figure 4 below. An electron moves with a velocity of 2 107 ms-1 parallel to it. Find the force acting on the electron. OR (ii)Calculate magnetic flux density of the magnetic field at the center of a circular coil of 5turns, having radius of 0.5 m and carrying a current of 5 A. Question 6. [2] Two substances A and B have their relative permeability slightly greater and slightly less than 1 respectively. What do you conclude about A and B as far as their magnetic materials are concerned? Question 7. [2] Draw a neat and labelled ray diagram to show the formation of a secondary rainbow. Page 5 of 10 Question 8 [2] What is the turns ratio i.e., transformer ratio, ns: np, in an ideal transformer which in-creases ac voltage from 220 V to 33000 V ? SECTION C 27 MARKS Question 9 [3] (a) An electric dipole of dipole moment p is placed in a uniform electric field E with its axis inclined to the field. Write an expression for the torque T experienced by the dipole in vector form. Show diagrammatically how the dipole should be kept in the electric field so that the torque acting on it is: (i) maximum (ii) zero Question 10 [3] (i) In a meter bridge circuit, resistance in the left hand gap is 2 and an unknown resistance X is in the right hand gap as shown in Figure 3 below. The null point is found to be 40 cm from the left end of the wire. What resistance should be connected to X so that the new null point is 50 cm from the left end of the wire ? Page 6 of 10 OR (ii) Figure 2 below shows two resistors R1 and R2 connected to a battery having an emf of 40 V and negligible internal resistance. A voltmeter having a resistance of 300 is used to measure potential difference across R1. Find the reading of the voltmeter. [3] Question 11 [3] Using Ampere s circuital law, obtain an expression for the magnetic flux density B at a point X at a perpendicular distance r from a long current carrying conductor. (Statement of the law is not required). Question 12 [3] For refraction through a prism , prove Where the terms have their usual meaning. OR (ii) Derive the relation between n1 , n2, u, v and R . Question 14 [3] (i)The radii of curvature of the faces of a double convex lens are 10 cm and 15 cm. If focal length of the lens is 12 cm, find the refractive index of the material of the lens. (ii)For which colour the refractive index of prism material is maximum and minimum?? Page 7 of 10 Question 15 [3] (i) Plot a labelled graph of /Vs/ where Vs is stopping potential versus frequency f of the incident radiation. (ii) State how will you use this graph to determine the value of Planck s constant. Question 16 [3] (a) A narrow beam of monochromatic light, PQ, is incident normally on one face of an equiangular glass prism of refractive index 1.45. When the prism is immersed in a certain liquid, the ray makes a grazing emergence along the other face (See figure).Find the refractive index of this liquid. [3] OR (b) When two thin lenses of focal lengths f1 and f2 are kept co axially and in contact, prove that their combined focal length f is given by: [3] 1/f=1/f1+1/f2 Question 17 [3] 1 and 2 are two batteries having emf of 34 V and 10 V respectively and internal resistance of 1 and 2 respectively. They are connected as shown in Figure 3 below. Using Kirchhoff s Laws of electrical networks, calculate the currents I1 and I2. SECTION D 15 MARKS Question 18 [5] Page 8 of 10 (i) (a) An alternating emf of 220 V is applied to a circuit containing a resistor R having resistance of 160 and a capacitor C in series. The current is found to lead the supply voltage by an angle 0 = tan-1 (3/4). (i) Calculate: (1) The capacitive reactance (2) Impedance of the circuit (3) Current flowing in the circuit (ii) If the frequency of the applied emf is 50 Hz. what is the value of the capacitance of the capacitor C ? Or (b) An ac generator generating an emf of = 300 sin (100 t) V is connected to a series combination of 16 F capacitor, 1H inductor and 100 resistor. Calculate: (i) Impedance of the circuit at the given frequency. (ii) Resonant frequency f0. (iii) Power factor at resonant frequency f0. Question 19 (a) Draw a labelled ray diagram of an image formed by a compound microscope, when the final image lies at the least distance of distinct vision (D). [3] (b) With regard to an astronomical telescope of refracting type, state how you will increase its : [2] (i) magnifying power (ii) resolving OR (a) Find critical angle for glass and water pair, given refractive index of glass is 1.62 and that of water is 1.33. [2] (b) Starting with an expression for refraction at a single spherical surface, obtain Lens Maker s Formula. [3] Question 20 [5] Resonant Series LCR Circuit. When the frequency of ac supply is such that the inductive reactance and capacitive reactance become equal, the impedance of the series LCR circuit is equal to the ohmic resistance in the circuit. Such a series LCR circuit is known as resonant series LCR circuit and the frequency of the ac supply is known as resonant frequency. Resonance phenomenon is exhibited by a circuit only if both L and C are present in the circuit. We cannot have resonance in a RL or RC circuit. A series LCR circuit with L = 0.12 H, C = 480 nF, R = 23 is Connect to a 230 V variable frequency supply. Page 9 of 10 Find the value of (i) source for which current amplitude is maximum. (ii) maximum current is (iii) maximum power is (iv) What is the Q-factor of the given circuit? (v) At resonance which physical quantity is maximum? Useful Constants & Relations: 1 Permittivity of vacuum 2 Constant for Coulomb s law 3 Constant in Magnetism 4 5 0 8 85 10-12F/m (1/4 0) 9 109 m/F ( 0/4 ) 1 10-7H/m Elementary charge e 1.6 X 10-19C Mass of an electron m 9 x 10-31kg Page 10 of 10

Formatting page ...

cynicbeast chat

Horizontal lines at:
Guest Horizontal lines at:
AutoRM Data:
Box geometries: