APPENDICES
4.1.1 QUESTION PAPERS OF PHYSICS, CLASS XII, 1992 : BASE FOR STUDY
PHYSICS Time allowed : 3 Hours] [Maximum Marks : 70
General Instructions for all sets
(i) All questions are compulsory.
(ii) Marks for each question are indicated against it.
(iii) Question numbers 1 to 10 are very short-answer questions, carrying I mark each. They are to be answered in one or two sentences each.
(iv) Question numbers 11 to 22 are short-answer questions, each carrying 2 marks. Answers to them should not exceed 30 words each.
(v) Question numbers 23 to 29 are also short-answer questions, each carrying 3 marks. Answers to them should not exceed 40 words each.
(vi) Question numbers 30 to 32 are long-answer questions, each carrying 5 marks. Answers to them should not normally exceed 70 words each.
(vii) Use Log Table, if necessary.
SET-1 Code No. 50/55/1/1
1. Draw lines of force to represent a uniform electric field. 1
2. What is geo-magnetic equator ? 1
3. When are the voltage and current in a LCR series AC circuit in phase ? 1
4. What is the power consumed in (i) purely inductive and (ii) purely capacitative AC circuits ? 1
5. Define elliptically polarised light. 1
6. State the path difference between two waves for destructive interference. 1
7. Define resolving power of a microscope. 1
8. What is the equivalent energy of a 10 mg mass ? 1
9. What is depletion region in a pn-junction ? 1
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10. What are comets composed of ? 1
11. Define coulomb. Calculate the charge carried by 12.5 x 10 18 electrons. 2
12. Define resistivity of a material. Does it depend on temperature ? 2
13. Show diagrams of AM and FM wave forms. 2
14. What are optical fibres ? Give their one use. 2
15. Define half-life of a radioactive substance. A radioactive substance decays to 1/32 of its
initial activity in 25 days. Calcuate its half-life. 2
16. Explain the phenomenon of fission. Given one representative equation. 2
17. Calculate the Coulomb force between a proton and a an electron separated by 0.8 x
10-15 M. 2
18. When a battery of e.m.f. E and internal resistance r is connected to a resistance P, a
current / flows through it. Derive a relation between E, /, r and R. 2
19. Give one use of each of the following
(i) microwaves,
(ii) infra-red waves,
(iii) ultra-violet radiation, and
(iv) gamma rays, 2
20. Derive an expression for the induced e.m.f. produced by changing the area of a rectangular
coil placed perpendicular to a uniform magnetic field. 2
21. An object is placed at a distance 5 cm from a convex lens of focal length 10 cm. Calculate
the position and magnification of the image. 2
22. Explain briefly stellar spectra, Give its one use. 2
23. State and explain Faraday's laws of electrolysis. Define electrochemical equivalent. 3
24. An electron travels in a circular path of radius 20 cm in a magnetic field of 2 x 10-3 T.
Calculate the speed of the electron. What is the potential difference through which the
electron must be accelerated to acquire this speed ? 3
25. Explain the differences between diamagnetic, paramagnetic and ferromagnetic substances. 3
26. Deduce the laws of refraction on the basis of Huygen's principle. 3
27. Explain the working of a simple microscope, and show that its magnification M is given by
M = 1-D/f,, where f = focal length and D = distance of distinct vision. 3
28. What is photoelectric effect ? Calculate the threshold frequency, of photon for
photoelectric emission from a metal of work function 0.1 eV. 3
29. Explain how you will convert a galvanometer into a voltmeter of a given range. 3
30. Define capacitance. Derive an expression for the capacitance of a cylindrical capacitor. 5
OR
State Gauss's law in electrostatics. Apply this to show that for a spherical shell, the electric
field inside the shell vanishes, whereas outside it, the field is as if all the charge had been
concentrated at the centre.
31. Explain through a labelled circuit diagram, the working of a transistor as an amplifier
(common emitter configuration). Obtain an expression for the voltage gain. 5
32. Derive an expression for the impedance of a coil in an AC circuit. A current of 1.1 A flows
through a coil when connected to a 110 V DC. When 110 V AC of 50 Hz is applied to the
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same coil, only 0.5 A current flows. Calculate the (i) resistance, (h) impedance and
(iii) inductance of the coil. 5
SET-2 Code No. 50/55/1/2
1. Define electric dipole moment. 1
2. What is angle of declination ? 1
3. Express quality factor (Q) in terms of L, C and R. 1
4. How can you obtain wattless current in an AC circuit ? 1
5. Define lumen. 1
6. What is the speed of light in glass having a refractive index 1.5 ? 1
7. Define resolving power of a telescope. 1
8. Give an equation representing the decay of a free neutron. 1
9. What types of charge carriers are there in a p-type semiconductor ? 1
10. What are shooting stars ? 1
11. Define coulomb. How many electrons will have a total electric charge of 1 coulomb ? 2
12. Define conductivity of a material. Give its Si unit. 2
13. Where is ozone layer situated in the atmosphere ? What role does it play for human
survival ? 2
14. Explain briefly the formation of mirage in deserts. 2
15. Give two important characteristics of nuclear forces. 2
16. Explain the phenomenon of fusion. Give one representative equation. 2
17. Calculate the Coulomb force between two protons separated by a distance of 1.6 X 10-15 M. 2
18. Apply Kirchhoff's laws to obtain the condition of balance in a Wheatstone's bridge. 2
19. Give four properties of electromagnetic waves. 2
20. Derive an expression for the work done in maintaining a steady current i o in an inductor. 2
21. The radii of curvature of a double convex lens are 15 cm and 30 cm and its refractive index
is 1.5. Calculate the focal length of the lens. 2
22. Explain briefly how the mass of a star can be determined. 2
23. State and explain Peltier effect. Define Peltier coefficient. 3
24. An electron after being accelerated through a potential difference of 10 4 V enters a uniform
magnetic field of 0.04 T perpendicular to its direction of motion. Calculate the radius of
curvature of its trajectory. 3
25. Explain the phenomenon of hysterisis in magnetic materials. 3
26. What do you understand by polarisation of light ? How can the transverse nature of light
be demonstrated experimentally ? 3
27. Draw a labelled diagram of a compound microscope and explain its working. 3
28. What is photoelectric effect ? Calculate the kinetic energy of a photoelectron (in eV) emitted
on shining light of wavelength 5 x 1 0-6m on a metal surface. The work function of the metal
is 0.15 eV. 3
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29. Explain how you will convert a galvanometer into an ammeter of a given range. 3
30. Define capacitance. Derive an expression for the capacitance of a parallel plate capacitor.
OR
Show that in a uniform electric field, a dipole experiences only a torque but no net force.
Derive expression for the torque. 5
31. Explain, through a labelled circuit diagram, the working of a transistor as an oscillator. 5
32. Derive an expression for the impedance of a LCR series AG circuit. A 40 W resistor, 3 mH
inductor and 2fF capacitor are connected in series to a 110 V, 5000 Hz AC source.
Calculate the value of the current in the circuit. 5
SET-3 Code No. 50/55/1/3
1. Define electric field at a point. 1
2. Name the elements of earth's magnetic field. 1
3. What does the Quality factor (Q) signify in a LCR AC circuit ? 1
4. Name one device through which power consumed in an AC circuit is zero. 1
5. Define elliptically polarised light. 1
6. Give a relation between path difference and wavelength for constructive interference between 1
two waves.
7. Define resolving power of a telescope. 1
8. What is the energy equivalent of a 6 mg mass ? 1
9. Which process causes depletion region in a np-junction ? 1
10. What are shooting stars ? 1
11. Define coulomb. Calculate the charge carried by 12.5 x 10 8 electrons. 2
12. State the conditions under which Ohm's law is not obeyed in a conductor. 2
13. At what height in the atmosphere, is the ozone layer situated ? What role does it play for
human survival ? 2
14. What are optical fibres ? Give their one use. 2
15. Define decay constant (lamda) of a radioactive substance. How is it related to half-life ? 2
16. Distinguish between fission and fusion. 2
17. Calculate the Coulomb force between two electrons separated by 0.8 x 10-15m, 2
18. Three resistance P, Q and R are connected in parallel. Derive an expression for their
equivalent resistance X. 2
19. Give four properties of electromagnetic waves. 2
20. Show that the induced e.m.f. produced by changing the area of a rectangular coil placed
perpendicular to a uniform magnetic field is- B/v, where the symobls have their usual
meanings. 2
21. Two lenses, one converging of power 8 Dipotres and the other diverging of power 4 Dioptres,
are combined together. Calculate the focal length and power of the combination. 2
22. Explain briefly how you will determine the mass of a star. 2
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23. State and explain Faraday's laws of electrolysis. Define faraday. 3
24. An electron moving with a speed 10 ms-1 enters a magnetic field of 5 X 10-3T in a direction
perpendicular to the field. Calculate (i) radius of the path and (it) frequency of revolution of
the electron. 3
25. Explain the phenomenon of hysterisis in magnetic materials. 3
26. Deduce the laws of refraction on the basis of Huygens principle. 3
27. Draw a labelled ray diagram of an astronomical telescope and explain its working.
28. What is photoelectric effect ? Calculate the threshold frequency of photon for photoelectric 3
emission from a metal of work function 0.05 eV.
29. Explain briefly how you will convert a galvanometer into a millivoltmeter of range 0-10 mV. 3
30. Three capacitors of capacitances X 1 X 2, and X 3 are connected (1) in series and (ii) in 3
parallel, Derive expressions for the equivalent capacitance X for each of these combinations. 5
OR
Define Capacitance. Show that the energy density in a parallel plate capacitor is 1/2 o E 2,
where E is the electric field. 5
31. Explain, through a labelled circuit diagram, the working of a transistor as an oscllator. 5
32. Derve an expression for the impedance of a coil in an AC circuit. A current of 2.2 A flows
through a coil when connected to a 220 V DC. When 220 V AC of 50 Hz is applied to the
same coil, only 1.0 A flows. Calculate the (i) resistance, (ii) impedance and (iii) inductance
of the coil. 5
SET-4 Code No. 50/55/1/4
1. Why two electric lines of force do not intersect ? 1
2. Define magnetic moment of a dipole and give its SI unit. 1
3. What is the physical meaning of Quality factor (Q) in a LCR, AC circuit. 1
4. What is the phase relationship between current and voltage in (i) an inductor and (h) a
capacitor in an AC circuit ? 1
5 Define circularly polarised light. 1
6. State the path difference between two waves for constructive interference. 1
7. What is the magnifying power of a telescope whose objectve and eyepiece have focal
lengths 180 cm and 3 cm respectively ? 1
8. What is the de Broglie wavelength of a 2 kg object moving wth a speed of 1 ms-1 ? 1
9. What causes depletion region in a np-junction ? 1
10. Define "light year". 1
11. How does the speed of an electrically charged particle affect its (i) mass and (ii) charge ? 2
12. Explain, under what conditions Ohm's law is not obeyed in a conductor. 2
13. Define Poynting's vector and give its SI unit. 2
14. Why do stars twinkle ? 2
15. Define decay constant (lamda) of a radiioactive substance. How is it related to half-life ? 2
16. Name the four essential components of a nuclear reactor. 2
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17. Calculate the Coulomb force between an alpha particle and a proton separated by 5.12 X 2
10-15 m.
18. Three resistances R, R 2 and R 3 are connected in parallel. Derive an expression for their 2
equivalent resistance R.
19. Explain Green house effect through a diagram. 2
20. What are eddy currents ? Give their one use. 2
21. Two lenses one diverging of power 2 Dioptres and the other covering of power 6 Dioptres 2
are combined together. Calculate the focal length and power of the combination,
22. Explain briefly how you will determine the size of a star. 2
23. Explain Seebeck effect. Discuss the thermoelectric series. 3
24. A chamber is maintained at a uniform magnetic field of 5 x 10-3 T. An electron wilt, a speed 3
5 x 10 7 ms-1 enters the chamber in a direction normal to the field. Calculate (i) radius of
the path and (ii) frequency of revolution of the electron.
25. Describe the construction and working of a tangent galvanometer 3
26. Deduce the laws of reflection on the basis of Huygen's principle. 3
27. Draw a labelled ray dagram of an astronomical telescope and explain its workng. Give, an 3
expression for its resolving power.
28. Show that the de Broglie wavelength of electron accelerated through a potential of V volts 3
can be expressed as lamda = h/v2meV.
29. Explain how you will compare the e.m.f.s. of Iwo cells by a potentiometer. 3
30. Define capacitance. Show that the energy density in a parallel plate capacitor is 5
where E is the electric field,
OR
Three capacitors of capacitances C 1, C 2 and C 3 are connected (i) in series and (ii) in
parallel. Derive expressons for the equivalent capacitance C for each of these combinations.
31. Explain through a labelled circuit diagram the working of a transistor as an oscillator. 5
32. Discuss the phenomenon of resonance in a LCR series AC circuit. A capacitor, a 15 ohm
resistor and 80 mH inductor are placed in series with a 50 Hz AC source. Calculate the 5
capacity of the capacitor if the current is observed in phase with the voltage
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4.1.2 UNITWISE DISTRIBUTION OF QUESTIONS : CLASS XII, PHYSICS, 1992 EXAM.
For All QPs of Delhi Region : Code No. 50/55/1/1 to 4
GRP Unit Topic (Marks) Question No. Remarks,
No. No. (As per Design of QP) -------------------------------- if any
Marks
1 2 3 5
1 Electrostatic (10) 1 11,17 - 30
I
3 Magnetism (4) 2 - 25 -
2 Current Electricity, Thermal,
II Chemicals & Magnetic effect - 12,18 23,24,29 -
of current (13)
4 E.M. Induction, AC & 3,4 13,19,20 - 32
E.M. Waves (13)
III 8 Universe (3) 10 22 - -
IV 5 Ray Optics, Wave Optics &
Optical Instruments (13) 5,6,7 14,21, 26,27 -
6. Atoms, Molecules & Nuclei,
Electrons & Photrons (8) 8 15,16, 28 -
V
7. Solids & Semiconductor (6) 9 - - 31
Total Marks : 70 1 * 10 2 * 12 3 * 7 5 * 3
=10 = 24 = 21 = 15
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4.2 PROFORMAS :
4.2.1. Proforma-I : Background informations for each question.
Central Board of Secondary Education : Delhi
Senior Secondary Exam. 1992
QUESTIONWISE ANALYSIS
(For each Question Paper)
Set No./Code No.-------------
Subject--------- Class -------- Max. Marks :-------- Duration :-------
(1) (2) (3) (4) (5) (6) (7) (8) (9)
S.No. of Instructional Specific Unit of Types of Marks Estimated Estimated Remarks,
the Objective Objective Syllabus Questions Difficulty time reqd. if any
Question K = Knowledge LA level (Minutes)
U = Understanding S-I/S-II A = Difficult
A = Application VSA B = Average
S = Skill C = Easy