ICSE Set Set1 Year Icse Physics2000 Set1.php Physics Exam Paper for students online
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Physics -
2000 (ICSE)
You are on questions
-All working, including rough work, should be done on the same sheet as, and adjacent to, the rest of the answer.
-The intended marks for questions or parts of questions are given in brackets ( ).
-Material to be supplied: Log tables including Trigonometric functions
-A list of useful physical constants is given at the end of this paper.
Q 1Answer all questions
briefly and to the point:- (Marks 20)
(i) State Gauss's theorem of electrostatics.
(ii) An alpha particle is accelerated through a potential difference of
2000 volt. What will be the increase in its energy in electron volt?
(iii) Assuming the earth as an isolated spherical conductor of radius
6400 km, calculate its electrical capacitance in farad.
(iv) If the potential difference applied across a variable resistor is
constant, draw a graph between the current in the resistor and the resistance.
(v) Find the equivalent resistance between the point 'a' and 'c' of the
given network of resistors (See Fig. 1).
(vi) Show with a labelled graph how thermo-emf varies with the
temperature of the hot junction of a thermocouple.
(vii) What is the function of shunt in an ammeter?
(viii) What is meant by 'Wattless' current?
(ix) Name the physical principle and one advantage in the use of optical
fibers.
(x) Can two independent monochromatic source of light be coherent?
Explain very briefly.
(xi) What is the relation between the refractive indices n1
and n2 if the behaviour of light rays is as shown in the following
Fig. 2?
Here n1 and n2 are the refractive indices of the
surrounding medium and the lens respectively.
(xii) What is the principle of global communication by satellites?
(xiii) State Brewster's law for polarisation of light.
(xiv) Two thin lenses-one convex and the other concave - of focal lengths
15 cm and 20 cm respectively are put in contact. Find the focal length of the
doublet lens.
(xv) Two stars three and four light years away from the earth have same
luminous intensity. Find the ration of the illuminance (intensity of
illumination) on the surface of the earth, normal to the starlight, produced by
each star.
(xvi) The historic experiment on the diffraction of electron confirmed a
new nature of electron. What is this new nature of electron? Who had proposed
it?
(xvii) Explain briefly why there is a maximum frequency for the X-rays
produced by an X-ray tube operating at a certain voltage.
(xviii) Draw circuit diagrams to illustrate forward biasing and reverse
biasing of a diode.
(xix) Name two alternative sources of energy and mention where they can
be used.
(xx) The half-life period of a radioactive substance is 16 hours. After
how much time will 6.25% of the material remain undecayed?
PART II
Answer six question in this part, choosing two questions each from the Sections A, B and C.
SECTION A
Answer two questions
Q 2 (a) Derive an expression
for the electric potential at a point due to a point charge. (Marks 4)
Q 2 (b) An electric flash lamp has 20 capacitors each of capacitance 5
F
connected in parallel. The lamp is operated at 100 volt. Calculate how much
energy will be radiated in a flash. (Marks 3)
Q 2 (c) Name one material whose resistivity decreases with rise in
temperature. Explain briefly on the basis of free electron theory why the
resistivity decreases. (Marks 2)
Q 3 (a)
State and explain Kirchoff's laws for electric circuits. What are the
conservation laws implied in each law? State the sign convention for current and
emf. Use the Fig. 3 given below for your explanation. (Marks 4)
Q 3 (b) An electron is moving vertically upwards in the uniform magnetic
field of the earth. The velocity of the electron is 2.0 x 106 m/s and
the horizontal component of earth's magnetic field is 0.32 x 10-4
tesla. Obtain the magnitude and direction of the force on the electron. (Marks
3)
Q 3 (c) Permanent magnets are made of special alloy while the core of
temporary magnets are made of soft iron. Why? (Marks 2)
Q 4 (a)
Define self inductance. Obtain the expression for the self inductance of a
solenoid, explaining steps with the help of a diagram. (Marks 3)
Q 4 (b) What is meant by back emf in a dc motor? The back emf in a dc motor,
delivering 3 kilowatts of mechanical power, is 180 volts when operating on 220
volt line. Determine the armature current and the motor resistance. (Marks 3)
Q 4 (c) In an LCR circuit with all components connected in series, the emf
and the current flowing in the circuit are given by the following equations:-
= 200 sin (314t + 
/6)
volts
I = 5 sin 314 t ampere
Obtain:
(i) the peak values of current and emf.
(ii) the frequency of the ac source.
(iii) the phase difference between current and emf. (Marks 3)
SECTION B
Answer two questions.
Q 5 (a) State Huygens'
principle. Explain with the help of a diagram the phenomenon of refraction of
waves on the basis of this principle. (Marks 3)
Q 5 (b) What is chromatic aberration in lenses? State the necessary
condition for an achromatic doublet. How are these conditions practically
achieved? (Marks 3)
Q 5 (c) Fraunhofer diffraction from a single slit of width 1.0 m
is observed with light of wavelength 500 nm. Calculate the half angular width of
the central maximum. (Marks 2)
Q 6 (a) Draw a neat ray
diagram of a simple microscope. Deduce the formula for its angular magnification
when the image is formed at the least distance of distinct vision. (Marks 3)
Q 6 (b) A beam of monochromatic light of wavelength 500 nm falls on two
parallel slits. The distance between the slits is 0.15 mm. Determine the width
of the interference fringes on a screen placed at a distance of 1.5 m from the
slits. (Marks 3)
Q 6 (c) Draw a sketch of electromagnetic spectrum, showing relative
positions of UV, IR, X-rays and microwaves with respect to visible light. State
approximate wavelengths of any two. (Marks 2)
Q 7 (a) With the help of neat
diagram describe with theory, Michelson's method for the determination of the
speed of light. What is the presently accepted nine digit value of the speed of
light? (Marks 4)
Q 7 (b) What is meant by pure and impure spectrum? Explain briefly how you
will set up a spectrometer to obtain pure spectrum. Draw a diagram of a
spectrometer and describe its parts. (Marks 4)
SECTION C
Answer two questions.
Q 8 (a) The ionisation
potential of hydrogen atom is 13.6 volt. Draw the energy level diagram showing
four levels. Calculate
(i) the energy of the photon emitted when an electron falls from the third orbit
to the second orbit.
(ii) the wavelength of this photon. (Marks 4)
Q 8 (b) Described briefly with a diagram and theory an experiment to
determine e/m of electron. (Marks 4)
Q 9 (a)
What is Compton scattering? State briefly its importance. (Marks 2)
Q 9 (b) When ultraviolet light of wavelength 300 nm is incident on a metal
plate, a negative potential of 0.54 volt is required to stop the emission of
photo electrons. Calculate the energy of the incident photon and the work
function for the metal in eV. (Marks 4)
Q 9 (c) Draw the circuit diagram of a half wave rectifier using a
semi-conductor diode. Explain briefly the function of each component. (Marks
2)
Q 10 (a)
Heavy water is suitable moderator in a nuclear reactor. Explain briefly why? (Marks
2)
Q 10 (b) Draw labelled diagrams to illustrate
(i) energy bands of a conductor, semiconductor and insulator.
(ii) npn and pnp transistors.
(iii) transistor as an amplifier (common emitter). (Marks 4)
Q 10 (c) What do you mean by AND gate? How will you realise AND gate with
junction diodes? (Marks 2)
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