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CBSE
SAMPLE QUESTION PAPER
Physics
(Theory) - Class XII (Code C)
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Time: 3 Hours Max. Marks:70
General Instructions:
1. All
questions are compulsory.
2. There are 30 questions in total.
Questions 1 to 8 carry one mark each, questions 9 to 18 carry two marks,
questions 19 to 27 carry three marks each and questions 28 to 30 carry five
marks each.
3. 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.
4. Use of
calculators is not permitted.
5. You may use
the following physical constants wherever necessary:
c = 3
× 108 ms–1
h = 6.6
× 10–34Js
e = 1.6
× 10–19 C
m0 = 4p
× 10–7 Tm A–1
Boltzmann
constant k = 1.38 × 1023 JK–1
Avogadro’s
number NA = 6.023 × 1023/mole
Mass
of neutron mn = 1.6 ×10–27 kg
1. What are the
factors on which the pole strength of a magnet depends? [1]
2. What is the
effect on the self inductance of a solenoid when a superconducting material is
inserted inside it?[1]
3. What is the
nature of induced electric field due to electromagnetic induction? [1]
4. What is the
energy of photon corresponding to a wavelength of 7000Å? [1]
5. What is the
focal length of a thin lens having lateral magnification +1? [1]
6. Which one
has large velocity; X-rays or cathode ray? [1]
7. What is the
value of ripple factor for half and full wave rectifiers? [1]
8. The input
signal for a common emitter amplifier is shown in figure below. [1]
Draw the
output signal corresponding to this input signal.
9. A particle of mass m having charge q is
moving parallel to y-axis with velocity v along straight line x = 2 enters into
magnetic field B along z-axis. Find the radius of the circular path followed by
it. [2]
10. A small spherical bob of mass 10 g and
carrying charge 10 mC is suspended with the help of a
light string from the centre of a large metallic plate having uniform surface
change charge density 2 × 10–4 C/m2. Find the tension in
the string. [2]
11. When the
temperature of a current carrying conductor is increased, how does the thermal
and drift speed of charge carrier’s change? [2]
12. Which one is
a good conductor of both heat current, iron or wood?
Why? [2]
13. “Electromagnetic
waves obey the Superposition principle”. Explain it. [2]
14. How will the
fringe width change if region between slit and screen in Young’s double slit
experiment is filled with water? [2]
15. What will
happen to the maximum kinetic energy of photoelectrons, if the frequency of
incident radiation becomes double? [2]
16. Write a brief
note on work function of a metal. [2]
17. Draw the
block diagram for a communication system. [2]
18. Is it
possible that a hydrogen atom in ground state can absorb a photon of energy
less than 10.2 eV? [2]
19. What is the
net force on an electric dipole (p) placed in a uniform electric field E? [3]
20. What are the
factors which affect the capacitance of a capacitor? [3]
21. State and
explain Kirchhoff’s first law (i.e., Junction Law). [3]
22. A solenoid
has volume V and core medium is air. Derive an expression for magnetic field
energy density in solenoid inside the solenoid is B. [3]
23. Define
quality factor for series LCR circuit and find expression for it. [3]
24. A thin rod of length R/6 is placed along the principal axis of
a concave mirror of radius of curvature R. If the image formed is real and
elongated and one end of image just touch the rod,
then find the magnification produced by the mirror. [3]
25. Write a short
note on spherical aberration. [3]
26. A radioactive
isotope has half life of T years. Find the time after which its activity
reduces to 12.5% of its original activity. [3]
OR
A sample of
radioactive element has mass 15 mg and has half life of 3.2 days. Find mass of
the element in the sample after 16 days.
27. Draw the
equivalent circuit for a transmission line and write expression for its
characteristic impedance. [3]
28. Two identical coils having radii r are
placed with their centres on x and y-axis as shown in
figure. Both coils are carrying equal magnitude of current I. Find the
direction and magnitude of net magnetic field at origin. [5]
OR
Show that the expression for
magnetic field at the centre of a regular polygon with n-sides is same as for
the magnetic field at the centre of circle, when
nà
8.
29. Derive an
expression for lens formula for a thin lens. [5]
or
Find the condition
for minimum deviation of an incident ray for a prism of refracting angle A.
30. Define
current amplification factor a and b and also find
relation between factor a and b for a transistor. [5]
or
The input
signals for A and B for the logic circuit shown in figure-1 are given in
figure-2.
Draw the output signal and write an
expression connecting Y, A and B.
| Tips: | 1. Students are also advise to spend first 5 minutes in reading and understanding question before start.
2. marks question : Student must solve these questions first
3. marks : It requires a little application part i.e., numerical as well as explanations.
4. marks : Good application of concepts require to solve these questions.I think student should try this session at the end of all category. r 5 marks : these part contains some fixed pattern of problem.
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Mr. D. K.Mishra
Physics |
