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Sample Paper-2- Raman Group
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CLASS XII
VSA
SA I
SA II
LA
(1
MARK)
(2 MARKS)
(3 MARKS)
(5 MARKS)
Electrostatics
1(1)
-
3(1)
4(1)
-
8(3)
Current electricity
------
2(1)
-----
-
5(1)
7(2)
1(1)
2(1)
-------
-
5(1)
8(3)
EMI & AC
1(1)
4(2)
3(1)
-------
-
8(4)
EMW
1(1)
2(1)
------
-------
-
3(2)
Optics
1(1)
2(1)
6(2)
5(1)
14(5)
Dual nature of matter
1(1)
-------
3(1)
-------
-
4(2)
Atoms & Nuclei
1(1)
2(1)
3(1)
-----
-
6(3)
Electronic devices
1(1)
------
6(2)
------
-
7(3)
Communications
system
-
2(1)
3(1)
-
-
5(2)
TOTAL
8(8)
16(8)
27(9)
4(1)
15(3)
70(29)
TOPIC
Magnetic effect
magnetism
TOTAL
&
(PHYSICS)
Class: XII
Maximum Marks: 70
Time allowed: 3 Hours
General Instructions:
All questions are compulsory.
There 29 questions in total. Questions 1 to 8 carry one mark each, questions 9 to16 carry two marks
each, questions 17 to 25 carry three marks each ,q-26 carry 4 mark(value based) and questions 27 to 29
carry five marks each.
There is no overall choice. However, an internal choice has been provided in one question of two marks
and one question of three marks and all the three questions of five marks each. You have to attempt only
one of the given choices in such questions.
(d)Use of calculators is not permitted.
(e)You may use the following physical constants wherever necessary:
1/40 = 9x109 Nm2C-2
1 a.m.u (U = 931.5 MeV
h = 6.6x10-34Js
Boltzmann’s constant. k=1.38x10-23J/K
c = 3x108 ms-1
1eV = 1.6x10-19J
-19
e = 1.6x10 C
Avogadro’s number N = 6.023x1023/mole
µ0 = 4π X 10-7 TmA-1
Mass of neutron mn = 1.6x10-27 Kg
Mass of electron me = 9.1x10-31 Kg
1. An electron is not deflected in passing through a certain region of space. Can we
be sure that there is no magnetic field in that region?
2. Why electric field lines are always normal to the conductor?
3. Compare nuclear density of two nuclei having mass number 27 and 125.
4. Draw an energy band diagram for n- type semiconductor.
5. A proton and an alpha particle have the same kinetic energy. What is the ratio of
their de Broglie wavelengths?
6. If the angle between polarizer and analyzer is 60°, by what factor does the
intensity of transmitted light change when passing through the analyser?
7. Name the characteristics of electromagnetic waves that (i) increases (ii) remains
constant in the electromagnetic spectrum as one moves from radiowave region
towards ultraviolet region.
8. What is power factor of LCR circuit at resonance?
9. A T V tower has a height of 75 m. What is the maximum distance and area up to
which this T V transmission can be received? Take radius of the earth 6.4 x 106 m.
10. The half –life of a radioactive substance is 30 s. Calculate:
(i ) the decay constant, and
(ii) Time taken by the sample to decay 3/4 of its initial value.
11. What will be the effect on the interference fringes in a Young’s double slit
experiment, if
( i ) monochromatic source is replaced by a source of white light,
( ii) the screen is moved away from the slit?
12 .Identify the constituent radiation of the electromagnetic spectrum which
(i)
is used for studying crystal structure.
(ii)
is absorbed by the ozone layer in the atmosphere.
(iii) produces intense heating effect.
(iv)
Is used to check the forge document.
13. State Lenz’s law. On which law of conservation it is based?
14. A power transmission line feeds input power of 33 MW at 3300 V to a step-down
transformer with its primary winding having 3000 turns. What should be the number
of turns in the secondary in order to get output power at 220 V.
15. Define the term’ angle of dip’. What is the value of angle of dip at magnetic
equator?
16. A piece of copper and another of germanium are cooled from room temperature
to 100 K. What will happen to their conductivity?
OR
How the resistivity of a conductor and an insulator varies with temperature? Show
with the help of graphs.
17. Sketch graph to show how charge Q given to a capacitor of capacitance C varies
with the potential difference V. Prove that the total energy stored in the capacitor is
½ CV2.
18. A series LCR circuit with L=5H , C =80µF and R = 40 ohm is connected to a
variable frequency source of 230 V,
( i) Determine the resonance frequency of the circuit.
( ii ) Obtain the impedance of the circuit and the amplitude of the current at
resonance.
19. Derive lens maker’s formula for a convex lens.
20.Two lenses of power +15D and -5D are in contact with each other forming a
combination of lens.
(a) What is the focal length of this combination?
(b) An object of size 3 cm is placed at 30 cm from this combination of lenses.
Calculate the position and size of the image formed.
21. Describe Davisson and Germer experiment to establish the wave nature of
electron. Draw a labeled diagram of the apparatus used.
22.Draw the output waveform at Y using the inputs A and B for the logic circuits
shown below.
OR
Show that the NAND gate is a universal gate.
23.Give a circuit diagram of a common emitter amplifier using a n-p-n transistor. Draw
the input and output wave form of the signal. Write the expression for voltage gain.
24. Draw block diagram of a communication system. What is meant by ‘detection’ of a
modulated carrier wave? Describe briefly the essential steps for detection.
25Define binding energy of a nucleus. Draw a curve between mass number and
binding energy per nucleon. Give two salient features of the curve.
26. Read the following story and answer the questions “Sagar is an Engineer working
in Samsung Company and posted at Guwahati, and his wife Geeta is a House wife
glued to TV program throughout the day. One day Geeta while manually operating the
TV found a continuous cracking sound in the TV and got frightened. She immediately
called Sagar who instructed Geeta to switch off the TV. Then Sagar contacted the
Airtel Digital TV customer care and instructed them something. That night after
returning from the office Sagar told Geeta that he has fixed the TV but it will again
become malfunctioning if she watches TV more than two hour a day. Next morning
Geeta started watching TV as usually for the whole day, without caring for what Sagar
has instructed.She thought that Sagar will not come to know about it.She continued
like that for two more days and in the third morning she found that only but the News
channel no other channel is available in the TV.She called Sagar back,but Sagar
simply said that its because she did not listen to the instruction that is why TV is
permanently Damaged.”- (i) Why the TV was producing the cracking sound,(ii)
Amongst Sagar and Geeta who was morally incorrect according to your
opinion?[Moral value based question]
27. State Huygens’s principle. Show with the help of suitable diagram, how this
principle is used to obtain the diffraction pattern due to single slit.
Draw a plot of intensity distribution and explain clearly why the secondary
maxima become weaker with increasing order of (n) of the secondary maxima.
OR
(a) In a Young’s double slit experiment deduce the condition for (i) Constructive and (ii)
destructive interference at a point on the screen. Draw a graph showing variation of
resultant intensity in the interference pattern against position x on the screen.
(b) Compare and contrast the pattern which is seen with two coherently illuminated
narrow slits in Young’s experiment with that seen for a coherently illuminated single
slit producing diffraction.
28. (i) Using Biot-Savart law derive an expression for the magnetic field due to a
current carrying loop at a point along the axis of the loop.
(ii) A long straight conductor carries a steady current I. The current is distributed
uniformly across its cross-section of radius a. Plot a graph showing the variation of
magnetic field B produced by the conductor with the distance r from the axis of the
conductor.
OR
Explain with the help of a labeled diagram the working principle of cyclotron. Show
that the cyclotron frequency does not depend on the speed of the particle. Write one of
the uses and point out one of the drawbacks of a cyclotron.
29. (a) When terminals of cells are connected by a wire of resistance 4 ohm, the p.d.
of the cell is 1.6 V. If a second wire of same resistance is connected in the parallel
with the first, the p.d. becomes 1.33V. What will be the p.d. when a third wire of
same resistance is connected in parallel with the other two? Also find the emf
and internal resistance of the cell.
(b) Two metallic wires of the same material have the same length but
cross
sectional area is in the ratio 1:2.They are connected in (i) series (ii)
parallel
across a potential difference V. Compare the drift velocities of
electrons in the
two wires in both
the cases (i) and (ii) .
OR
(a)Twelve similar wires each of resistance r are connected to form a cube .
Calculate the equivalent resistance between the ends of a side.
(b) Balancing length of the potentiometer wire of two primary cells of emf E1 and E2
are 250cm and 400cm respectively. What will be the balancing length for their series
combination when their emfs.
(a ) support each other?
(b) oppose each other ?
KENDRIYA VIDYALAYA SANGATHAN GUWAHATI REGION
REGIONAL LEVEL SECOND PRE BOARD EXAMINATION 2011- 2012
CLASS XII
PHYSICS
MARKING SCHEME
Q.No
Value points
Marks
1
-Z axis
1
2
Diagram of equipotential surfaces due to a dipole
1
3
Nuclear density is independent of mass no. i.e. 1:1
1
Energy
band
diagram
for
p-type
semiconductor
4
1
5
Formula + Correct answer , 1:2
½+½
6
Formula + Correct answer , Intensity reduces to 1/4
½+½
7
Frequency, velocity
½+½
8
CosΦ=1
½+½
9
Correct formula, range , area
½+1+½
10
Formula + Correct answer for each
½ +½ +½ +½
11
Colored central maxima, fringe width increases
1+1
12
½ for each correct answer
½+½+½+½
13
Statement + conservation of energy
1+1
14
Formula +correct answer i.e. 200
½+ 1½
15
Definition + correct answer
1+1
16
Conductivity of Cu increases and for Ge decreases
1+ 1
OR
1 for each correct graph
17
18
19
Correct graph + Derivation
Resonance frequency, impedance, current amplitude
½ for each correct formula and ½ for each correct answer
Ray diagram
+
Derivation
1+2
1+1+1
1
2
20
Focal length
Lens formula
Position
Size of image
1
½
½
1
21
Diagram
Establishment of wave nature of electron
Output is in accordance with OR Gate
OR
Make OR,AND and NOT gate with the help of NOR Gate
1
2
1+2
22
1+1+1
23
24
25
26
27
28
Circuit ,input and output wave form,
Formula for voltage gain
Block diagram
Detection
Essential steps for detection
Definition of B.E.
B.E. curve
Two salient features
2+ ½
½
1
1
1
1
1
1
26. (i) Crackling sound is due to charging of the glass screen due to
polarisation
(ii) Both Sagar and Geeta are morally incorrect- as Sagar being an
Engineer knew the reason but he lied,and played trick by ordering only news
channel pack.Geeta is wrong- as she didnot listen to her well wisher,as the
excessive Tv watching would herm her eyes as well her mental health.
Huygens’s Principle
Diffraction pattern due to single slit
Intensity Distribution Curve
Explanation for weaker secondary maxima
OR
Deduction of expression for constructive and destructive interference
Variation of intensity with distance from centre of screen
Difference between interference and diffraction
Derivation
1
Direction of magnetic field
Variation of B w.r.t. distance
3
1
2
1
1
3
1
1
2½
½
2
OR
Principle
Diagram
Construction & working
1
1
2
One use
½
½
One drawbacks
29
(a) Pd after connecting third wire
E.M.F. of cell
Internal resistance of cell
(b) Comparison of drift velocities in case (i) 2:1
Comparison of drift velocities in case (ii) 1:1
OR
(a) Current Distribution
Equivalent resistance ( 7/12 )r
1
1
1
1
1
1
2
(b) Balancing length in case (a) 650cm
Balancing length in case (b) 150 cm
1
1