ARIF KHAN

54 Pages·2012·37.94 MB·English

Exclusively Think. Learn. Succeed
PHYSICS
IIT-JEE | MEDICAL | FOUNDATION | BOARDS
ARIF KHAN
Er. Mohd. Arif Khan, a renowned Physics
faculty, having teaching experience of more than
17 years. He is graduate (B.Tech.) in electrical
Engg. and taught in top institutes like Aakash
Institute- New Delhi, Vision Kota (HOD) Kota,
Rajeshthan, Sachedeva New P.T. College,
Springdale College, Bareilly and in Varanasi he
taught in CATJEE for four years. Now he runs
his own individual physics classes for IIT-JEE/
MEDICAL/FOUNDATIONS/BOARDS.
ARIF R ACADEMY
TM
IIT-JEE | MEDICAL | FOUNDATION | BOARDS
D 64/94 A3 Sigra (Near Shubham Hospital)
09415441100, 09369110100 Varanasi
[email protected]; www.arifacademy.com
Series P1 Code No. DRML/1

Candidates must write the code on
Roll no.
the title page of the answer-book.

 Please check that this question paper contains 4 printed pages.

 Code number given on the right hand side of the question paper should be written on the title page of the answer-book

by the candidate.
 Please check that this question paper contains 26 questions.

 Please write down the Serial Number of the question before attempting it.

 15 minutes time has been allotted to read this question paper.

PHYSICS (Theory)
Time allowed : 3 hours Maximum Marks : 70
General Instructions :
(i) All questions are compulsory. There are 26 questions in all.
(ii) This question paper has five sections: Section A, Section B, Section C, Section D and Section E.
(iii) Section A contains five questions of one mark each, Section B contains five questions of two marks
each, Section C contains twelve questions of three marks each, Section D contains one value based
question of four marks and Section E contains three questions of five marks each.
(iv) 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 the three questions of five marks weightage. You have to
attempt only one of the choices in such questions.
(v) You may use the following values of physical constants wherever necessary.
c = 3  108 m/s
h = 6.63  1034 Js
e = 1.6  1019 C
 = 4  107 T m A1
0
 = 8.854  1012 C2N1 m2
0
1 = 9  109 N m2 C2
4
0
m = 9.1  1031 kg
e

ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 1
[BOARD PAPER: PHYSICS]

Section A

1. A wire of resistivity  is stretched to four times its length. What will be its new resistivity? [1]

2. What is the effect on the electric force between two charges, if a dielectric slab is introduced between
them? [1]

3. Why do magnetic field lines prefer to pass through ferromagnetic substances than through air? [1]

4. What is the value of the critical angle for a material of refractive index 2? [1]

5. What do you mean by the term transmission channel? [1]

Section B

6. What will be the current through the 9 resistor and the potential drop across the 5 resistor? [2]

7. Use the mirror formula to show that a convex mirror always produces a virtual image independent of
the location of the object. [2]
Or
How will the resolving power of a compound microscope be affected if (i) the frequency of light used
to illuminate the object is increased, and (ii) the focal length of the objective is increased?

8. A photon and an electron have the same de-Broglie wavelength. Which one has greater total energy?
[2]

9. What is the Bohr quantization condition for the angular momentum of the electron in the third orbit?
[2]

10. An n-type semiconductor has a large number of free electrons but still it is electrically neutral. Explain.
[2]

Section C

11. Two capacitors of capacitances C = 2 F and C = 6 F arranged in series are connected in parallel
1 2
with a third capacitor C = 4.5 F. The arrangement is connected to a 9 V battery. Calculate the total
3
energy stored in the capacitors. [3]

12. Determine the voltage drop across the resistor R in the circuit given in the figure. [3]
1

ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 2
[BOARD PAPER: PHYSICS]

13. Write an expression for Biot-Savart law in vector form. Derive an expression for magnetic field at the
centre of a circular current carrying coil of radius r having n turns. [3]

14. What is self-induction?
A 200 turns coil of self-inductance 30 mH carries a current of 6 mA. Find the magnetic flux linked with
each turn of the coil. [3]

15. State three properties of electromagnetic waves. [3]

3
16. A sunshine recorder globe of 15 cm radius is made up of glass of refractive index . A ray enters the
2
globe parallel to the axis. Find the position from the centre of the sphere where the ray crosses the axis.
[3]

17. If two coherent sources are far apart, will you be able to detect interference pattern? Explain.
4
A double slit apparatus is immersed in a liquid of refractive index . It has a slit separation of 1 mm
3
and the distance between the plane of slits and screen is 1.33 m. Calculate the fringe width, if the slits
are illuminated by a parallel beam of light whose wavelength in air is 630 nm. [3]

18. What do you mean by photoelectric effect? The work function for a certain metal is 4.2 eV. Will this
metal give photoelectric emission for incident radiation of wavelength 330 nm? [3]

19. State the values of kinetic energy, potential energy and total energy of an orbiting electron of hydrogen
atom as per Bohr's theory. How are the kinetic energy, potential energy and the total energy related to?
[3]
Or
Derive the relation N = N et for radioactive decay.
t 0

20. Define the terms 'potential barrier' and 'depletion region' for a pn junction diode. What will be the
effect on the thickness of depletion region, if the pn junction is (i) forward biased and (ii) reverse
biased? [3]

21. In the figure given below, circuit symbol of a logic gate and two input wave-forms A and B are shown.
[3]

(i) Name the logic gate.
(ii) Write the truth table.
(iii)Give the output waveform.

22. A schematic arrangement for transmitting an message signal (20 Hz to 20 kHz) is given below.

ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 3
[BOARD PAPER: PHYSICS]

Give two drawbacks from which this arrangement suffers. Give a block diagram of an alternative
arrangement for the transmission and reception of the message signal. [3]

Section D

*23. A group of 25 students of a school were going on an educational excursion to a thermal power plant in
their bus. At the thermal power plant, they came to know that it produced 600 kW electric power at
4000 V which was to be transported to a place 20 km away from the power plant for consumers usage
at 200 V. Students did not understand the utility of such a high voltage as the supply was only 200 V.
Next day, they put this question to their teacher. Physics teacher thought it to be an important question
and therefore, explained electrical energy transmission requirements to the whole class. Based on the
above paragraph, answer the following questions:
(i) Electric power can be transported either directly with a cable of large current carrying capacity or
by using a combination of step-up and step down transformers at two ends. Which is the most
preferred method and why?
(ii) What will be the power dissipation during transmission, if the direct transmission method with a
cable of 0.4  km1 is used?
(iii)What are the values displayed by (a) the teacher and (b) the students? [4]

Section E

24. Define the term electric field intensity. Write its SI unit. Derive an expression for the electric field
intensity at a point on the axis of an electric dipole.
If the electric dipole is free to move in a uniform electric field, explain its motion when it is placed
parallel to the electric field. [5]
Or
Derive an expression for the energy stored in a capacitor of capacitance C, charged to a potential V.
Also obtain the expression for energy density in terms of permittivity of free space and electric field.

25. In an ac circuit, a capacitance C, an inductor L and a resistor R are connected in series. Derive an
expression for the impedance and the phase angle. What is the impedance at resonance? Also obtain the
expression for the resonant frequency of the circuit. [5]
Or
Explain with the help of a labelled diagram, the principle, construction and the working of an ac
generator. Also derive the expression for the induced emf.

26. Derive an equation relating u, v and R in case of refraction at a convex spherical surface separating a
medium of refractive index n from a medium of refractive index n . State the assumptions made in
1 2
your derivation. [5]
Or
Draw a neat labelled diagram to show how the image of a distant object is formed by an astronomical
refracting telescope in normal adjustment. Obtain an expression for its magnifying power and state any
one advantage of an astronomical telescope of the reflecting type over a refracting type.
ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 4
Series P2 Code No. RSPL/2

Candidates must write the code on
Roll no.
the title page of the answer-book.

 Please check that this question paper contains 4 printed pages.

 Code number given on the right hand side of the question paper should be written on the title page of the answer-book

by the candidate.
 Please check that this question paper contains 26 questions.

 Please write down the Serial Number of the question before attempting it.

 15 minutes time has been allotted to read this question paper.

PHYSICS (Theory)
Time allowed : 3 hours Maximum Marks : 70
General Instructions :
(i) All questions are compulsory. There are 26 questions in all.
(ii) This question paper has five sections: Section A, Section B, Section C, Section D and Section E.
(iii) Section A contains five questions of one mark each, Section B contains five questions of two marks
each, Section C contains twelve questions of three marks each, Section D contains one value based
question of four marks and Section E contains three questions of five marks each.
(iv) 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 the three questions of five marks weightage. You have to
attempt only one of the choices in such questions.
(v) You may use the following values of physical constants wherever necessary.
c = 3  108 m/s
h = 6.63  1034 Js
e = 1.6  1019 C
 = 4  107 T m A1
0
 = 8.854  1012 C2N1 m2
0
1 = 9  109 N m2 C2
4
0
m = 9.1  1031 kg
e

Section A
1. Can test charge q be equal to zero? If not why? [1]
0

2. If the potential difference applied across a variable resistor is constant, draw a graph between the
current in the resistor and the resistance. [1]

3. State the advantage of using a radial magnetic field in a moving coil galvanometer. [1]

ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 1
[TEST PAPER : PHYSICS]

4. A convex lens of focal length 0.2 m and a concave lens of focal length 5 cm are kept along the same
axis with distance x between them. Find the distance x, if a parallel beam of light falling on the convex
lens leaves through the concave lens as a parallel beam. [1]

5. What do you mean by the process modulation? [1]

Section B
6. Draw a circuit diagram of a metre bridge to determine the resistance of a given wire. Write the formula
used. [2]

7. Use the mirror formula to show that for an object lying between the pole and the focus of a concave
mirror, the image formed is always virtual in nature. [2]
Or
How will the magnifying power of a refracting type astronomical telescope be affected on increasing
for its eyepiece (i) the aperture, and (ii) the focal length?

8. Show that the de Broglie wavelength  of the electrons of energy E is given by the relation  = h(2
mE)1/2. [2]

9. Bohr's principle of quantization of angular momentum is not a postulate but an essential condition.
Explain. [2]

10. What are donor energy levels? [2]

Section C
11. Four charges equal to Q are placed at the four corners of a square and a charge q is at its centre. Find
the value of q, if the system is in equilibrium. [3]

12. Find the effective resistance between the points X and Y of the electrical circuit shown in the figure. [3]

13. Derive an expression for the force per unit length acting in each of the two straight parallel metallic
linear conductors carrying currents. Also define ampere. [3]

14. What is motional emf? What is its magnitude? State the rule which is applied to determine the direction
of induced emf. [3]

15. The electric field of a plane electromagnetic wave in vacuum is represented by
  x
E 0,E 0.5cos2108t ,E 0
X y   c Z
(i) What is the direction of propagation of electromagnetic wave?
(ii) Find the wavelength of the wave.
(iii)Calculate the component of associated magnetic field. [3]

16. Define critical angle with reference to total internal reflection.
Calculate the critical angle for glass-air surface if a ray of light which is incident in air on the glass
surface is deviated through 15, when angle of incidence is 45. [3]
ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 2
[TEST PAPER : PHYSICS]

17. In a Young's double slit experiment, the separation between two slits is d and the wavelength of the
light is . The intensity of light falling on the slit 1 is four times the intensity of light falling on the slit
2. State the number of maximum observed, if (i) d =  and (ii)  < d < 2. [3]

18. What is stopping potential? How is it related to maximum velocity of ejected electrons? Find the
stopping potential, if the maximum kinetic energy of emitted photoelectrons from plate is 0.5825 eV.
[3]

19. Draw the graph showing the variation of binding energy per nucleon with mass number A. State clearly
how the release in energy in the processes of nuclear fission can be explained. [3]
Or
The total energy of the electron in the first excited state of hydrogen atom is about 3.4 eV.
(i) What is the kinetic energy of the electron in this state?
(ii) What is the potential energy of the electron in this state?
(iii)Which of the two will change, if choice of zero of potential energy is changed?

20. Distinguish between conductors, semiconductors and insulators with the help of energy band diagrams.
[3]

21. You are given two circuits as shown in figures (a) and (b). Write the truth tables for the given circuits
and identify the logic operations performed by the two circuits. [3]

22. What is meant by detection of a signal in a communication system. Draw a block diagram of a detector
of AM signal and briefly explain how the original signal is obtained from the modulated wave. [3]

Section D
*23. In a laboratory, students were doing an experiment using a galvanometer. One student asked his
classmate about the internal parts of the galvanometer. But he could not answer. They asked about the
galvanometer from his teacher. Teacher listened to their queries patiently and discussed the topic to the
whole class.
(i) What are the values displayed by the students?
(ii) What is the principle of galvanometer?
(iii)Why is it called moving coil galvanometer?
(iv) Why are the pole pieces of the magnet made concave shaped? [4]

Section E
24. Derive an expression for the magnitude of electric field intensity at any point along the equatorial line
of a short electric dipole. For a short electric dipole, find the ratio of electric field intensities at two
equidistant points from the centre of dipole: one along the axial line and another on the equatorial line.
[5]
Or
(a) Define electric flux. Write its dimension.
(b) State Gauss's law, use it to deduce the expression for the electric field due to a uniformly charged
thin spherical shell at points (i) inside and (ii) outside the shell.

ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 3
[TEST PAPER : PHYSICS]

25. State the principle of a step-up transformer with the help of a labelled diagram and explain its working.
Write any two important sources of energy loss in a transformer and state how these can be
minimized. [5]
Or
(a) Derive an expression for the average power consumed in a series LCR circuit connected to
alternating current source in which the phase difference between the voltage and the current in the
circuit is .
(b) An inductor of unknown value, a resistor of 10  and a capacitor of 100 F are connected in series
to a 200 V, 50 Hz alternating current source. Calculate the inductance of the inductor and the
current amplitude if the power factor is unity.

26. With the help of a ray diagram, illustrate the formation of the final image of an object in a compound
microscope. Derive an expression for its magnifying power. How can the magnifying power be
increased? [5]
Or
What do you mean by diffraction of light? State the essential condition for diffraction of light. Explain
it due to a narrow single slit and the formation of a pattern of fringes obtained on the screen. Draw a
graph showing the variation of intensity with angle  in the experiment. State one feature which
distinguishes the observed pattern from the double slit interference pattern.
ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 4
Series P3 Code No. RSPL/3

Candidates must write the code on
Roll no.
the title page of the answer-book.

 Please check that this question paper contains 4 printed pages.

 Code number given on the right hand side of the question paper should be written on the title page of the answer-book

by the candidate.

 Please check that this question paper contains 26 questions.

 Please write down the Serial Number of the question before attempting it.

 15 minutes time has been allotted to read this question paper.

PHYSICS (Theory)
Time allowed : 3 hours Maximum Marks : 70
General Instructions :
(i) All questions are compulsory. There are 26 questions in all.
(ii) This question paper has five sections: Section A, Section B, Section C, Section D and Section E.
(iii) Section A contains five questions of one mark each, Section B contains five questions of two marks
each, Section C contains twelve questions of three marks each, Section D contains one value based
question of four marks and Section E contains three questions of five marks each.
(iv) 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 the three questions of five marks weightage. You have to
attempt only one of the choices in such questions.
(v) You may use the following values of physical constants wherever necessary.
c = 3  108 m/s
h = 6.63  1034 Js
e = 1.6  1019 C
 = 4  107 T m A1
0
 = 8.854  1012 C2N1 m2
0
1 = 9  109 N m2 C2
4
0
m = 9.1  1031 kg
e

ARIF ACADEMY (D 64/94 A3 Sigra (Near Shubham Hospital, Varanasi)) (9415441100) |www.arifacademy.com| Page 1