Mission Examination: आइएससी-12वीं के Physics विषय का Model Paper और एग्जामिनेशन टिप्स

जागरण संवाददाता, मेरठ। काउंसिल फार द इंडियन स्कूल सर्टिफिकेट एग्जामिनेशन यानी सीआइएससीई के इंडियन स्कूल सर्टिफिकेट यानी आइएससी-12वीं के फिजिक्स की परीक्षा चार मार्च को होगी। पेपर स्कोरिंग होता है और इस पेपर की तैयारी के लिए परीक्षार्थियों के पास एक महीने से अधिक समय शेष है।

फिजिक्स का पेपर भी विज्ञान वर्ग के दोनों अभ्यर्थी, यानी पीसीएम फिजिक्स, केमिस्ट्री और मैथ्स और पीसीबी फिजिक्स केमिस्ट्री व बायोलाजी, विद्यार्थियों को पढ़ना पढ़ता है। परीक्षार्थियों के अभ्यास के लिए आइएससी-12वीं के फिजिक्स का माडल पेपर प्रकाशित किया जा रहा है।

माडल पेपर के साथ अच्छी तैयारी के लिए सेंट मेरीज एकेडमी की फिजिक्स शिक्षिका सीमा सिंघल जरूरी सुझाव दे रही हैं। उनके अनुसार परीक्षार्थी सेमीकंडक्टर्स को पेपर के अन्य हिस्से के साथ ही तैयार करते हैं। अंतिम समय के लिए कतई न छोड़ें। यह बेहद स्कोरिंग और आसान है लेकिन अंतिम समय में बहुत अधिक कठिन प्रतीत होता है।

  MOCK PREBOARD EXAMINATION – CLASS XII PHYSICS - TIME : 3Hrs. (MM70)

All questions are compulsory.

This question paper is divided into four sections, A, B, C and D.

Attempt all the sections (Internal choice is given)

SECTION A [1 X 14 =14]

Q.1.(I) Select the correct options:                 [1 X 7 = 7]

(i) Electric potential at an equipotential surface due to point charge 10- 9 C is 9 V. The radius of equipotential surface is:

(a) 1m (b)2m (c) 1.6 m (d) none [1]

(ii) Consider 10 identical capacitors each of capacitance 5 µF. The ratio of minimum and maximum possible values of the capacitance that can be obtained from them is

(a) 1 : 50 (b) 1 : 100 (c) 50 : 1 (d) 100 : 1 [1]

(iii) Two wires A and B of equal masses and of the same material are taken. The diameter of the wire A is half the diameter of the wire B. If the resistance of the wire A is 24 Ω, the resistance of the wire B is:

(a) 1.2 ohm (b) 12 ohm (c) 1.5 ohm (d) none of these [1]

(iv) Current flowing through the circuit is maximum when:

(a) XL = Xc (b) XL > Xc (c) XL < Xc (d) Z > R [1]

(v) To which regions of the electromagnetic spectrum of wavelength belong to 250 nm:

(a) X - ray (b) ultraviolet radiation (c) infrared radiation (d) none of these [1]

(vi) When light wave travels from air to glass:

(a) its wavelength decreases (b) Its wavelength increases (c) there is no change in wavelength (d) Its frequency decreases. [1]

(vii) Assertion: The magnetic field produced by a current carrying solenoid is independent of its length and cross-sectional area.

Reason : the magnetic field inside the solenoid is zero at its centre.

(a) Both assertion and reason are correct and the reason is a correct explanation of the assertion.

(b) Both assertion and reason are correct, but reason is not a correct explanation of the assertion.

(c) Assertion is true, but reason is false.

(d) Both assertion and reason are false. [1]

(II) Answer the following questions in brief; [1 X 7 = 7]

(i) A candle is placed at a distance 3cm in front of a concave mirror of radius of curvature 24 cm. Locate the position of image of candle [1]

(ii) Draw the electric field lines of force due to two equal and similar negative point charges. [1]

(iii) The radius of the first orbit of the electron of a hydrogen atom is 5.3 X 10– 11 m. What is the radius of its second orbit? [1]

(iv) Distinguish between diamagnetic and paramagnetic substances in terms of its relative permeability and magnetic susceptibility. [1]

(v) A charged 30 µF capacitor is connected to a 27 mH inductor. What is the angular frequency of free oscillations of the circuit? [1]

(vi) Give the expression for power factor in a L-R circuit in the terms of resistance R and the inductive reactance X. [1]

(vii) What is the condition of first minima in diffraction through a single slit of width e? [1]

SECTION B [2 X 7 = 14]

Q.2. Five-point charges, each having +q charge, are placed at five corners of a regular hexagon of side L. Find the magnitude of the force acting on – q charge placed at the centre. [2]

Q.3. Three capacitors of capacitance C1 = 3µF, C2 = 6 µF & C3 = 10 µF are connected to a 50 volt battery, as shown in the figure. Calculate equivalent capacitance & equivalent potential energy stored in the system. [2]

Q.4. A current I flows through a metallic wire of radius r and free electrons in it drift with a velocity vd. Calculate the drift velocity of the free electrons through the wire of the same material, having double the radius, when same current flows through it. [2]

OR

Draw a ray-diagram to show how an image is produced by a pair of total reflecting prism arranged as in a periscope. [2]

Q.5. A long, straight wire is turned into a loop of radius 10 cm (as shown in figure). If a current of 8A is passed through the loop. Find magnetic field at C, the centre of the loop. [2]

Q.6.(i) What is the function of a shunt in a galvanometer?

(ii) State two factors on which sensitivity of a moving coil galvanometer depends [1+1]

Q.7. Which of the following has the shortest wavelength? Lowest frequency?

microwaves, ultraviolet rays, infrared rays and X Rays? [2]

Q.8.(i) An ideal inductor does not consume any power even though both V and I are non-zero. Explain in brief. [1]

(ii) When the current changes from 8 A to 2 A in 3 X 10-2 seconds in a coil, then the induced emf in it is 2 volts. Find the self-inductance of the coil. [1]

OR

Draw a labelled graph to show variation in intensity of diffracted light with angular position in a single-slit diffraction experiment. [2]

SECTION C [3 X 9 = 27]

Q.9. A 0.5 m long metal rod PQ completes the circuit as shown. The area of the circuit is perpendicular to the magnetic field of flux density, 0.15 T. If the resistance of the total circuit is 3Ω. Calculate the force needed to move the rod in direction, as indicated with a constant speed of 2 m/s. Calculate the work done per second needed to move the rod PQ. [3]

Q.10.(i) Focal length of glass (µ = 1.5) lens in air is 30 cm and in a liquid is 120 cm, find the refractive index of the liquid. [2]

(ii) Draw IV characteristics of a forward biased p-n junction diode. [1]

Q.11. If wavelength of first line of Lyman series in hydrogen atom is 1215 Å, calculate the wavelength of first and second line of Barmer series.

OR

Obtain the relation for the current I = I0 sin(t -) for a pure inductor across which an alternating emf = 0 sin is applied. Draw its phasor diagram also. [3]

Q.12(i). State any two differences between primary rainbow and secondary rainbow. [2]

(ii) A ray of light is incident on a prism whose refractive index is 1.52 at an angle of 40°. If the angle of emergence is 60°, calculate the angle of prism. [1]

Q.13.(i) Draw the circuit diagram of a full wave rectifier using a p-n Junction diode.

(ii) Why does reverse saturation current increases with increase in temperature in p-n junction diode ?[3]

Q.14. (i)Write an expression for Biot-Savart’s law in vector form.

(ii) A current is flowing in a thin straight metallic conductor of infinite length. Using above law find expression for the magnetic field at a distance from it. [3]

Q.15. Using Gauss’s theorem derive an expression for the electric intensity due to a charged thin spherical shell at (i) external point (ii) surface point & (iii)internal point. [3]

Q.16. Determine the binding energy of the nucleus of 8O16. Given mass of Proton = 1.007825 u, mass of neutron = 1.008665 u and atomic mass of 8O16 = 15.994915 u. [3]

OR

In a nuclear reactor, what is the function of: (i) the moderator, (ii) the shield (iii) the coolant. [3]

Q.17. Explain the following briefly (i) LED (ii) photo diode (iii) Solar cell. [3]

SECTION D [5 X 3 = 15]

Q.18. (i)Obtain an expression for refraction at a single convex spherical surface i.e., the relation between n1( rarer medium), n2 (denser medium), the object distance u, image distance v and radius of curvature R. [3]

(ii) A potential metre wire of length 200 cm has a resistance of 20 Ω. It is connected in series with the resistance of 10 Ω and an accumulator of emf 6 V, having negligible internal resistance. A source of 2.4 V is balanced against a length L of the potentiometer wire. Find the value of L. [2]

OR

Q.18.(i) Obtain an expression for the fringe width in Young’s double slit experiment. State any two ways of increasing the fringe width without changing the source of light. [3]

(ii) The deviation produced for violet, yellow and red lights for crown glass are 3.75°, 3.25 °and 2.86° respectively. Calculate the dispersive power of the crown glass. [2]

Q.19. (i) E1 and E2 are two batteries having emf 3 V and 4 V and internal resistance of 2 Ω and 1 Ω, respectively. They are connected, as shown in the figure, using Kirchhoff’s law of electrical circuits, Calculate current I1 and I2. [3]

(ii) Draw labelled ray diagram of an image formed by a compound microscope when the final image lies at least distance of distinct vision. [2]

OR

Q.19.(i) Using Bohr’s postulates deduce an expression for radius r of electron in nth orbit and its velocity v there. Further with its help find out the frequency new of the emitted electromagnetic wave when electron jumps from higher energy state n2 to a lower energy state n1. [3]

(ii) Derive laws of reflection using Huygens’ wave theory. [2]

Q.20. Read the passage given below and answer the given questions:

Photoelectric effect is the phenomenon of emission of electrons from a metal surface when radiation of suitable frequency fall on them. The emitted electrons are called photoelectrons and the current so produced is called photoelectric current .

(i) What is the effect of intensity of light on emission of photoelectrons emitting per second?

(ii) How is stopping potential V0 related with K.Emax?

(iii) Give the name of any device based on photoelectric effect.

(iv) How is the maximum kinetic energy related with frequency of radiation of photoelectrons?

(v) Calculate the momentum of a photon of green light of λ = 500nm in SI unit. [5]

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Useful Constants & Relations:

1. Constant for Coulomb’s law (1/40) = 9 × 109 Nm2/C2

2. Permeability of vacuum (µ0) = 4 × 10–7 H/m

3. Speed of light in vacuum c = 3 × 108 m/s

4. Plank’s Constant h = 6.6 × 10–34 Js

5. Charge of a proton e = 1.6 × 10–19 C

6. leV = 1.6 × 10–19 J

7. 1 nm 1 × 10–9 m

8. amu 1u = 931 Mev

कम महत्वपूर्ण सोच कर कुछ न छोड़ें

आइएससी परीक्षार्थियों के लिए यह बेहद जरूरी है कि बोर्ड परीक्षा के लिए निर्धारित पाठ्यक्रम में से कुछ भी न छोड़ें। महत्वपूर्ण व कम महत्वपूर्ण मानकर कोई बिंदु छोड़ना बुद्धिमानी नहीं होगी। आइएससी की ओर से केवल कठिन प्रश्न ही नहीं पूछे जाते हैं बल्कि आसान प्रश्न भी पूछ लिए जाते हैं। पाठ्यक्रम में निहित थ्योरी के साथ ही न्यूमेरिकल्स को भी विस्तार से पढ़ें और हल करें। फिजिक्स में व्याप्त फार्मूला को हर दिन रिवाइज करें यानी दोहराएं। पिछले सालों के बोर्ड परीक्षा पेपर जरू हल करें और निर्धारित समय के भीतर हल करने की कोशिश करें जिससे समय प्रबंधन का भी अभ्यास हो सके।

डेरिवेशन को लिखकर अभ्यास करें

फिजिक्स के पेपर में हर बिंदु बेहद बारीकी से और समझकर अभ्यास करने की जरूरत है। इसी कड़ी में डेरिवेशन का अभ्यास हमेशा लिखकर करें और निरंतर करें। फिजिक्स के प्रश्नपत्र के समय, न्यूमेरिकल प्रश्नों के उत्तर लिखते समय उत्तर में यूनिट जरूर लिखें। केवल माडल पेपर पर ही भरोसा न करें बल्कि अपने विषय को विस्तार से पढ़ें, समझें और तैयार करें। अब जो भी समय शेष रह गया है उसमें योजनाबद्ध तरीके से पाठ्यक्रम का ठीक से रिवीजन करें।

स्वास्थ्य का विशेष ध्यान रखें

टाइम-टेबल के अनुरूप पढ़ाई करना बेहद जरूरी है लेकिन लगातार लंबे घंटे तक पढ़ने की बजाय ब्रेक लेकर पढ़ें। ब्रेक के दौरान शारीरिक व मानसिक स्थितियों में मददगार उपक्रम को अपने साथ जोड़ सकते हैं। ब्रेक में स्वजन से भी बाबत और खान-पान का विशेष ध्यान रखें।