1.
When an object is placed between f and 2f of a
concave mirror, would the image formed be (i) real or virtual and (ii)
diminished or magnified ?
2.
Draw a plot showing the variation of de
Broglie wavelength of electron as a function of its K. E.
3.
Why is the frequency of outgoing and incoming
signals different in a mobile phone ?
4.
A particle of mass ‘m’ and charge ‘q’ moving
with velocity ‘v’ enters the region of uniform magnetic field at right angle to
the direction of its motion. How does its kinetic energy get affected ?
5.
Figure shows a current carrying solenoid
moving towards a conducting loop. Find the direction of the current induced in
the loop.
6.
Distinguish between
unpolarised and a linearly polarised light. Describe, with the help of a diagram, how unpolarised light gets
linearly polarised by scattering
7.
Why does white light disperse when passed
through a glass prism ? Using lens maker’s formula, show how the focal length
of a given lens depends upon the colour
of light incident on it.
8.
Using the graph shown in the figure for
stopping potential V/s the incident Frequency of photons, calculate Planck’s
constant.
9.
Complete the following
nuclear reactions :
OR
If both the number of protons and neutrons in a nuclear reaction is
conserved, in what way is mass converted
into
energy (or vice verse) ? Explain
giving one example.
10. Using the concept of drift velocity of charge carriers in a
conductor, deduce the relationship between current density and resistivity of the conductor.
11. Define the following using suitable diagrams : (i) magnetic
declination and (ii) angle of dip. In what direction will compass needle point when kept at the (i) poles and (ii)equator ?
12. Derive the expression for the magnetic
energy stored in a solenoid in terms of magnetic field B, area A and length l of the solenoid
carrying a steady current I.How does this magnetic energy per unit volume
compare with the electrostatic Energy density stored in a parallel plate capacitor ?
13.
A circuit containing an 80 mH inductor and a 250 µF capacitor in series
connecte to a 240 V, 100 rad/s supply.
The resistance of the circuit is
negligible.(i) Obtain rms value of current.(ii) What is the total average power
consumed by the circuit ?
14.
Answer the following questions :
(i) Why is the thin ozone layer on top
of the stratosphere crucial for human survival ? Identify to which a part of electromagnetic spectrum does this radiation
belong and write one important application of the radiation.
(ii) Why are infrared waves referred to as
heat waves ? How are they produced ?
What role do they play in maintaining the
earth’s warmth through the greenhouse effect ?
15. Define the term ‘critical angle’ for a
pair of media.
A
point source of monochromatic light ‘S’ is kept at the centre of the bottom of
a cylinder of radius 15.0 cm. The cylinder contains
water (refractive index 4/3) to a height of 7.0 cm. Draw the ray diagram and
calculate the area of water surface through which the light emerges in air.
16. Which two of the following lenses L1, L2
and L3 will you select as objective and eyepiece for constructing best possible
(i)
telescope (ii) microscope ? Give reason to support your answer.
17. Explain by drawing a suitable diagram
that the interference pattern in a double slit is actually a superposition of
single
slit
diffraction from each slit. Write two basic features which distinguish the
interference pattern from those seen in
a
coherently illuminated single slit.
18. Distinguish between n-type and p-type
semi-conductors on the basis of energy band diagrams. Compare their
conductivities
at absolute zero temperature and at room
temperature.
19. (a) Given a block diagram of a
generalized communication system.
Identify the boxes ‘X’ and ‘Y’ and write
their functions.
(b) Distinguish between “Point to Point” and
“Broadcast” modes of communication
20. An electric dipole of dipole moment 
is placed in a uniform electric
field
.Obtainthe expression for the
torque
experienced by the dipole. Identify two pairs of perpendicular vectors
in the expression.
is placed in a uniform electric
field.Obtainthe expression for the
torque
experienced by the dipole. Identify two pairs of perpendicular vectors
in the expression.
21. (a) Two spherical conductors of radii R1
and R2 (R2 > R1) are charged. If they are connected by a conducting wire,
find
out the ratio of the surface charge densities on them.
(b) A steady current flows in a metallic conductor of non-uniform
cross-section. Which of these quantities
is constant
along the conductor : current, current density, electric field, drift
speed ?
22. In the two electric circuits shown in the
figure, determine the readings of ideal ammeter (A) and the ideal voltmeter
(V).
OR
In
the circuit shown in the figure, find the current through each resistor.
23. Ameen had been getting huge electricity
bill for the past few months. He was upset about this. One day his friend
Rohit, an electrical engineer by profession, visited hishouse. When he pointed
out his anxiety about this to Rohit, his friend found that Ameen was using
traditional incandescent lamps and using old fashioned air conditioner. In
addition there was no proper earthing in the house. Rohit advised him to use
CFL bulbs of 28 W instead of 1000 W – 220 V and also advised him to get proper
earthing in the house. He made some useful suggestion and asked him to spread
this message to his friends also.
(i) What qualities/values, in your opinion
did Rohit possess ?
(ii) Why CFLs and LEDs are better than
traditional incandescent lamps ?
(iii) In what way earthing reduces
electricity bill ?
24. (a) Draw a schematic arrangement of
Geiger-Marsden experiment showing the scattering of a-particles by a thin foil
of gold. Why is it that most of the a-particles go right through the foil
and only a small fraction gets scattered at large angles ?
Draw the trajectory of the a-particle in the coulomb field of a nucleus.
What is the significance of impact parameter and what information can be obtained regarding
the size of the nucleus ?
(b)
Estimate the distance of closest approach to the nucleus (Z = 80) if a 7.7 MeV
a-particle before it comes momentarily to rest and reverses its direction.
OR
(a)
Write two important limitations of Rutherford model which could not explain the
observed features of atomic spectra.
How were these explained in Bohr’s model of hydrogen atom ? Use the
Rydberg formula to calculate the wavelength
of the Hα line. (Take R = 1.1 X107
m–1).
(b)
Using Bohr’s postulates, obtain the expression for the radius of the nth orbit
in hydrogen atom.
25. (a) Figure shows the input waveform which
is converted by a device ‘X’ into an
output waveform. Name the device and explain its working using the proper
circuit. Derive the expression for its voltage gain and power gain.
(b) Draw the transfer characteristic of a
base biased transistor in CE configuration.Explain clearly which region of the
curve
is
used in an amplifier.
OR
(a) Explain briefly, with the help of circuit
diagram, the working of a full wave rectifier. Draw its input and output waveforms.
(b) Identify the logic gate equivalent to the
circuit shown in the figure.Draw the truth table for all possible values of
inputs A and
B.
26. (a) Use Biot-Savart law to derive the expression
for the magnetic field due to a circular coil of radius R having N turns at a point on the axis at a distance ‘x’ from its centre. Draw the magnetic field
lines due to this coil.
b) A current ‘I’ enters a uniform circular
loop of radius ‘R’ at point M and flows out at N as shown in the figure.Obtain the net magnetic field at the centre of the loop.
(a) Show how Biot-Savart law can be alternatively
expressed in the form of Ampere’s
circuital law. Use this law to obtain the
expression for the magnetic field inside a
solenoid of length ‘l’, cross-sectional area ‘A’ having ‘N’ closely
wound turn
and carrying a steady current ‘I’. Draw
the magnetic field lines of a finite solenoid carrying current I.
(b) A straight horizontal conducting rod of
length 0.45 m and mass 60 g is suspended
by two vertical wires at its ends. A current
of 5.0 A is set up in the rod through the wires.Find the magnitude and
direction of the magnetic field which should be set up in order that the tension
in the wire is zero.
