XAM IDEA Physics Class 12th Board Question Bank

743 Pages·2017·9.87 MB·English

P H Y S I C S
Examination Papers
2008–2015
CONTENT
n CBSE Examination Paper–2008 (Delhi) 3
n CBSE Examination Paper–2008 (All India) 37
n CBSE Examination Paper–2009 (Delhi) 71
n CBSE Examination Paper–2009 (All India) 103
n CBSE Examination Paper–2009 (Foreign) 131
n CBSE Examination Paper–2010 (Delhi) 161
n CBSE Examination Paper–2010 (All India) 186
n CBSE Examination Paper–2010 (Foreign) 213
n CBSE Examination Paper–2011 (Delhi) 239
n CBSE Examination Paper–2011 (All India) 273
n CBSE Examination Paper–2011 (Foreign) 303
n CBSE Examination Paper–2012 (Delhi) 333
n CBSE Examination Paper–2012 (All India) 358
n CBSE Examination Paper–2012 (Foreign) 390
n CBSE Examination Paper–2013 (Delhi) 419
n CBSE Examination Paper–2013 (All India) 451
n CBSE Examination Paper–2013 (Foreign) 480
n CBSE Examination Paper–2014 (Delhi) 507
n CBSE Examination Paper–2014 (All India) 535
n CBSE Examination Paper–2014 (Foreign) 567
n CBSE Examination Paper–2015 (Delhi) 595
n CBSE Examination Paper–2015 (Ajmer) 613
n CBSE Examination Paper–2015 (Allahabad) 633
n CBSE Examination Paper–2015 (Bhubaneshwar) 654
n CBSE Examination Paper–2015 (Chennai) 674
n CBSE Examination Paper–2015 (Guwahati) 695
n CBSE Examination Paper–2015 (Panchkula) 714
n CBSE Examination Paper–2015 (Patna) 732
n CBSE Examination Paper–2015 (Foreign) 750
CBSE EXAMINATION PAPERS
DELHI–2008
Time allowed : 3 hours Maximum marks : 70
General Instructions:
(a) All questions are compulsory.
(b) There are 30 questions in total. Questions 1 to 8 carry one mark each, questions 9 to 18 carry two marks
each, questions 19 to 27 carry three marks each and questions 28 to 30 carry five marks each.
(c) There is no overall choice. However, an internal choice has been provided in one question of two
marks, one question of three marks and all 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 values of physical constants wherever necessary:
c=3´108 ms-1 h =6×626´10-34 Js
e=1×602´10-19 C m =4p´10-7 TmA-1
0
1
= 9 × 109 Nm2C– 2
4pe
o
Boltzmann’s constant k =1×381´10-23 JK-1
Avogadro’s number N =6×022´1023/mole
A
Mass of neutron m =1×2´10-27 kg
n
Mass of electron m =9×1´10-31kg
e
Radius of earth = 6400 km
CBSE (Delhi) SET–I
®
1. What is the direction of the force acting on a charge particle q, moving with a velocity v in a
®
uniform magnetic field B ?
2. Name the part of the electromagnetic spectrum of wavelength 10-2 m and mention its one
application.
3. An electron and alpha particle have the same de Broglie wavelength associated with them. How
are their kinetic energies related to each other ?
4. A glass lens of refractive index 1×5 is placed in a through of liquid. What must be the refractive
index of the liquid in order to make the lens disappear ?
5. A 500mC charge is at the centre of a square of side 10 cm. Find the work done in moving a charge
of 10 mC between two diagonally opposite points on the square.
6. State the reason, why heavy water is generally used as a moderator in a nuclear reactor.
7. How does the fringe width of interference fringes change, when the whole apparatus of Young’s
experiment is kept in a liquid of refractive index 1.3 ?
4 Xam idea Physics—XII
8. The plot of the variation of potential difference across a combination of three identical cells in
series, versus current is as shown below. What is the emf of each cell ?
V
6V
0 1A i
9. Derive the expression for the electric potential at any point along the axial line of an electric dipole ?
10. Define magnetic susceptibility of a material. Name two elements, one having positive susceptibility
and the other having negative susceptibility. What does negative susceptibility signify ?
11. The oscillating magnetic field in a plane electromagnetic wave is given by
B =(8´10-6)sin[2´1011t +300px]T
y
(i) Calculate the wavelength of the electromagnetic wave.
(ii) Write down the expression for the oscillating electric field.
12. Prove that an ideal capacitor, in an a.c. circuit does not dissipate power.
OR
Derive an expression for the impedance of an a.c. circuit consisting of an inductor and a resistor.
13. A nucleus 23Ne undergoes b-decay and becomes 23Na. Calculate the maximum kinetic energy of
10 11
electrons emitted assuming that the daughter nucleus and anti-neutrino carry negligible kinetic
energy.
ìmass of 23Ne=22×994466uü
10
ï ï
ímass of 1213Na =22×989770uý
ï1 u = 931×5MeV/c2 ï
î þ
14. Distinguish between an intrinsic semiconductor and P-type semiconductor. Give reason, why a
P-type semiconductor crystal is electrically neutral, although n >>n ?
h e
15. Draw a ray diagram of a reflecting type telescope. State two advantages of this telescope over a
refracting telescope.
16. A ray of light passing through an equilateral triangular glass prism from air undergoes minimum deviation
when angle of incidence is 3/4th of the angle of prism. Calculate the speed of light in the prism.
17. The given inputs A, B are fed to a 2-input NAND gate. Draw the output wave form of the gate.
A
Input
B
Input
t t t t t t
1 2 3 4 5 6
Examination Papers 5
18. A transmitting antenna at the top of a tower has a height of 36 m and the height of the receiving
antenna is 49 m. What is the maximum distance between them, for satisfactory communication in
the LOS mode ? (Radius of earth = 6400 km).
19. How is a wavefront defined ? Using Huygen’s construction draw a figure showing the
propagation of a plane wave refracting at a plane surface separating two media. Hence verify
Snell’s law of refraction.
20. A metallic rod of length l is rotated at a constant angular speed w, normal to a uniform magnetic
field B. Derive an expression for the current induced in the rod, if the resistance of the rod is R.
21. The figure adjoining shows the V-I characteristics of a semiconductor diode.
I (mA)
100
80
60
40
20
100 80 60 40 20O
V 0.2 0.4 0.6 0.8
br
10 V (Volt)
20
30
I (mA)
(i) Identify the semiconductor diode used.
(ii) Draw the circuit diagram to obtain the given characteristic of this device.
(iii) Briefly explain how this diode can be used as a voltage regulator.
22. An inductor 200 mH, capacitor 500 mF, resistor 10W are connected in series with a 100 V, variable
frequency a.c. source. Calculate the
(i) frequency at which the power factor of the circuit is unity.
(ii) current amplitude at this frequency.
(iii) Q-factor.
23. Prove that the current density of a metallic conductor is directly proportional to the drift speed of
electrons.
OR
A number of identical cells, n, each of emf E, internal resistance r connected in series are charged
by a d.c. source of emf E¢, using a resistor R.
(i) Draw the circuit arrangement.
(ii) Deduce the expressions for (a) the charging current and (b) the potential difference across the
combination of the cells.
24. A potentiometer wire of length 1 m is connected to a driver cell of emf 3 V as shown in the figure.
When a cell of 1×5 V emf is used in the secondary circuit, the balance point is found to be 60 cm.
On replacing this cell and using a cell of unknown emf, the balance point shifts to 80 cm.
6 Xam idea Physics—XII
3V
A B
1.5 V
R
(i) Calculate unknown emf of the cell.
(ii) Explain with reason, whether the circuit works, if the driver cell is replaced with a cell of emf 1 V.
(iii) Does the high resistance R, used in the secondary circuit affect the balance point ? Justify our
answer.
25. An electromagnetic wave of wavelength l is incident on a photosensitive surface of negligible
work function. If the photo-electrons emitted from this surface have the de-Broglie wavelength l ,
1
prove that l=æç2mcö÷l2.
1
è h ø
26. The energy level diagram of an element is given below. Identify, by doing necessary calculations,
which transition corresponds to the emission of a spectral line of wavelength 102×7 nm.
- 0.85 eV
A
- 1.5 eV
B C
- 3.4 eV
D
- 13.6 eV
27. Draw a plot of the variation of amplitude versus w for an amplitude modulated wave. Define
modulation index. State its importance for effective amplitude modulation.
28. (a) Using Biot-Savart’s law, derive an expression for the
magnetic field at the centre of a circular coil of radius R, l R x O
I
number of turns N, carrying current I.
(b) Two small identical circular coils marked 1 and 2 carry
equal currents and are placed with their geometric axes
perpendicular to each other as shown in the figure. Derive
an expression for the resultant magnetic field at O. x
2 R
O'
I
OR
Draw a schematic diagram of a cyclotron. Explain its underlying principle and working, starting
clearly the function of the electric and magnetic fields applied on a charged particle.
Deduce an expression for the period of revolution and show that it does not depend on the speed
of the charged particle.
Examination Papers 7
29. (a) For a ray of light travelling from a denser medium of refractive index n to a rarer medium of
1
n
refractive index n , prove that 2 =sini , where i is the critical angle of incidence for the media.
2 c c
n
1
(b) Explain with the help of a diagram, how the above principle is used for transmission of video
signals using optical fibres.
OR
(a) What is plane polarised light? Two polaroids are placed at 90° to each other and the
transmitted intensity is zero. What happens when one more polaroid is placed between these two,
bisecting the angle between them ? How will the intensity of transmitted light vary on further
rotating the third polaroid?
(b) If a light beam shows no intensity variation when transmitted through a polaroid which is
rotated, does it mean that the light is unpolarised ? Explain briefly.
30. (a) Using Gauss law, derive an expression for the electric field intensity at any point outside a
uniformly charged thin spherical shell of radius R and charge density s C/m2. Draw the field lines
when the charge density of the sphere is (i) positive, (ii) negative.
(b) A uniformly charged conducting sphere of 2×5 m in diameter has a surface charge density of
100mC/m2. Calculate the q
(i) charge on the sphere (ii) total electric flux passing through the sphere.
OR
10 cm 10 cm
(a) Derive an expression for the torque experienced by an electric dipole
kept in a uniformly electric field.
(b) Calculate the work done to dissociate the system of three charges
–4q 10 cm +2q
placed on the vertices of a triangle as shown.
Here q=1×6´10-10 C.
CBSE (Delhi) SET–II
Questions different from Set – I
1. Name the part of the electromagnetic spectrum of wavelength 102 m and mention its one
application.
2. An electron and alpha particle have the same kinetic energy. How are the de-Broglie wavelengths
associated with them related?
3. A converging lens of refractive index 1×5 is kept in a liquid medium having same refractive index.
What would be the focal length of the lens in this medium?
6. How does the angular separation of interference fringes change, in Young’s experiment, if the
distance between the slits is increased?
11. Draw a ray diagram of an astronomical telescope in the normal adjustment position. State two
draw backs of this type of telescope.
12. Calculate the distance of an object of height h from a concave mirror of focal length 10 cm, so as
to obtain a real image of magnification 2.
8 Xam idea Physics—XII
13. Draw the output wave form at X, using the given inputs A, B for the logic circuit shown below.
Also identify the gate.
A
X
B C
t t t t t
1 2 3 5 6
t
4
A
Input
B
Input
®
15. Derive an expression for the potential energy of an electric dipole of dipole moment p in an
®
electric field E.
18. Prove that an ideal inductor does not dissipate power in an a.c. circuit.
OR
Derive an expression for the self-inductance of a long air-cored solenoid of length l and number of
turns N.
19. Define conductivity of a conductor. Explain the variation of conductivity with temperature in
(a) good conductors, (b) ionic conductors.
24. How is a wavefront defined ? Using Huygen’s construction draw a figure showing the
propagation of a plane wave reflecting at the interface of the two media. Show that the angle of
incidence is equal to the angle of reflection.
25. A coil of number of turns N, area A, is rotated at a constant angular speed w, in a uniform magnetic
field B, and connected to a resistor R. Deduce expressions for :
(i) Maximum emf induced in the coil
(ii) Power dissipation in the coil.
CBSE (Delhi) SET–III
Questions different from Set – I & II
1. Name the absorbing material used to control the reaction rate of neutrons in a nuclear reactor.
2. State the reason, why two independent sources of light cannot be considered as coherent sources.
5. An electron and a proton have the same de Broglie wavelength associated with them. How are
their kinetic energy related to each other?
7. How does the power of a convex lens vary, if the incident red light is replaced by violet light ?
9. Draw a ray diagram of a compound microscope. Write the expression for its magnifying power.
12. If the output of a 2 input NOR gate is fed as both inputs A and B to another NOR gate, write down
a truth table to find the final output, for all combinations of A, B.
Examination Papers 9
15. The oscillating electric field of an electromagnetic wave is given by:
E =30sin[2´1011t +300px]Vm-1
y
(a) Obtain the value of the wavelength of the electromagnetic wave.
(b) Write down the expression for the oscillating magnetic field.
16. Obtain the expression for the mutual inductance of a pair of coaxial circular coils of radii r and
R(R>r) placed with their centres coinciding.
20. The energy levels of an element are given below:
- 0.85 eV
A
- 1.5 eV
C
- 3.4 eV
B D
- 13.6 eV
Identify, using necessary calculations, the transition, which corresponds to the emission of a
spectral line of wavelength 482 nm:
24. An inductor of unknown value, a capacitor of 100mF and a resistor of 10W are connected in series
to a 200 V, 50 Hz a.c. source. It is found that the power factor of the circuit is unity. Calculate the
inductance of the inductor and the current amplitude.
25. Prove that the current density of a metallic conductor is directly proportional to the drift speed of
electrons through the conductor.
OR
Define resistivity of a conductor. Plot a graph showing the variation of resistivity with temperature
for a metallic conductor. How does one explain such a behaviour, using the mathematical
expression of the resistivity of a material.
26. A metallic rod of length l is rotated at an angular speed w, normal to a uniform magnetic field B.
Derive an expression for the (i) emf induced in the rod (ii) heat dissipation, if the resistance of the
rod is R.