These are the model papers for physics exams to practice with keys for cbse board exams which includes these lessons
Electrostatics
Current electricity
Magnetism
Alternating current
Electromagnetic induction
Electromagnetic waves
Ray optics
Wave optics
Atoms
Nuclei
Semiconductors
MODEL PAPER - 4
PHYSICS
Maximum Marks: 70 Time Allowed:3 hours
General Instructions:
1) There are 33 questions in all. All questions are compulsory.
2) This question paper has five sections: Section A, Section B, Section C, Section D and
Section E.
3) All the sections are compulsory.
4) Section A contains sixteen questions, twelve MCQ and four Assertion Reasoning based
of 1 mark each, Section B contains five questions of two marks each, Section C contains
seven questions of three marks each, Section D contains two case study based questions
of four marks each and Section E contains three long answer questions of five marks
each.
5) There is no overall choice. However, an internal choice has been provided in one
question in Section B, one question in Section C, one question in each CBQ in Section
D and all three questions in Section E. You have to attempt only one of the choices in
such questions.
6) Use of calculators is not allowed.
7) You may use the following values of physical constants where ever necessary.
i. c = 3 x 108 m/s
ii. me = 9.1 x10-31 kg
iii. e = 1.6 x 10-19 C
iv. µ0 = 4π x 10-7 Tm𝑨 −𝟏
v. h = 6.63 x10-34 J s
vi.
ε0 = 8.854 x10-12 𝑪 𝟐𝑵−𝟏𝒎−𝟐
vii. Avogadro’s number = 6.023 X 𝟏𝟎𝟐𝟑 per gram mole
SECTION- B
Q. Question Marks
No.
17 A conductor of length ‘l’ is connected to a dc source of potential ‘V’. If the 2
length of the conductor is tripled by gradually stretching it, keeping ‘V’
constant, how will
(i) drift speed of electrons and
(ii) resistance of the conductor be affected? Justify your answer.
18 (a) Arrange the following electromagnetic waves in the descending order of 2
their wavelengths.
Microwaves, γ-rays, Ultraviolet radiation, Visible light
(b) Write one use of above waves having lowest and highest wavelength.
19 The refractive index of a material of a concave lens is μ1. It is immersed in a 2
medium of refractive index μ2. A parallel beam of light is incident on the lens.
Trace the path of emergent rays when
, i) μ2 > μ1
ii) μ2 < μ1
20 Draw suitable graphs to show the variation of photoelectric current(Ip) with 2
collector plate potential (V) for
i) a fixed frequency but different intensities I1 > I2 > I3.
ii) a fixed intensity but different frequencies ν1 > ν2 > ν3.
21 Explain, with the help of a suitable diagram, how (i) depletion layer and (ii) 2
potential barrier is formed in a p-n junction diode.
OR
Draw a circuit diagram of a full wave rectifier. Draw the input and output
waveforms indicating clearly the functions of the two diodes used.
SECTION-C
22 Two long straight parallel conductors carry study currents I1 and I2 separated by a 3
distance d. If the current are flowing in the same direction, show how the
magnetic field setup in one produces an attractive force on the other. Obtain the
expression for this force. Hence define one ampere.
OR
(a) With the help of labelled diagram, explain the underlying principle and
working of a moving coil galvanometer.
(a) What is the function of (i) uniform radial field (ii) soft iron core, in such a
device?
23 Three lenses focal lengths + 10 cm, - 10 cm and +30 cm are arranged coaxially 3
as in the figure given below. Find the position of the final image formed by the
combination.
24 Draw a plot showing the variation of binding energy per nucleon with mass 3
number A. Write two important conclusions which you can draw from this plot.
25 Define self inductance and write its SI unit. Obtain an expression of self 3
inductance of a solenoid of length ‘l’ cross-sectional area ‘A’ having ‘N’ no. of
turns.
26 In the network shown in fig. Calculate currents I1, I2 and I3. 3
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