Q.1. A solid conducting
sphere of radius 1 m has , in steady state a charge of +10m C. What would the
electric potential at 0.5m from the centre be ? (1)
Q.2. Give the expression for
the energy of an electric dipole in its stable equilibrium in a
region of uniform electric field , E.
Q.3. When electric current
is passed through the Junctions of two dissimilar metals , heat is
evolvedat one of the junctions. On reversing the direction of current ,
cooling takes place at the samejunction. Name the effect? (1)
Q.4. State two factors on
which the current sensitivity of a moving coil galvanometer
depends. (1)
Q.5. Why is the core of a
transformer laminated? (1)
Q.6. Why are microwaves used in Radar? (1)
Q.7. Give the relation
between current-gain and voltage-gain of a transistor.(1)
Q.8. The image of an object formed by a lens on the screen is not
sharply focussed. Suggest a method to get clear focussing of the image on the screen without
disturbing the position of the object,lens or the screen.(1)
Q.9. Two large square metal
plates of area 10 sq. mts. each are kept 3 mm apart in vaccum. One
plate is connected to the +ve terminal and the other, to the -ve terminal of a 2 V battery. Calculate how much electric charge can be stored on this set up? (2)
Q.10. Calculate the electric
current drawn from the cell in the circuit :
E = 1.5
V
R = 1.1W
Q.11. In an
alternating current circuit, the voltage and current are represented
as :
V=100 sin(314 t) Volt
I =100 cos(314 t - p
/3) Ampere
(a) Calculate the power dissipated in the circuit.
(b) Is the reactance of the circuit, capacitative or inductive?(2)
Q.12. Find the thickness of
a plate which will produce a charge in optical path equal to half
the wavelength of light passing through it normally. Refractive index of the plate is.(2)l
Q.13. The distance between a
thin convex lens and a convex mirror is 10 cm. A student is able to
remove parallax of a pin with its image formed by this combination, by placing the pin 12 cm from the convex lens. If the focal length of the lens is 10 cm , calculate the radius of curvature of the spherical mirror.(2)
Q.14. An alpha particle of
energy 2 MeV moves along a circular path in a region of uniform
magnetic field.Calculate the energy of a proton if it also describes a circular path of same radius for the same field. (2)
Q.15. Four p-n
junctions are connected as shown and a resistance RL is given.Complete the
circuit so that an alternating current can be rectified into a unidirectional current. (2)
Q.16. Write in brief the
method to determine the distance of an inferior planet from the sun. (2)
Q.17. Two insulating small
spheres are rubbed against each other and then placed at a
distance of 3 m apart.If they attract each other with a force of 25.6 N, calculate the number of electrons transferred from one sphere to the other during rubbing.(3)
Q.18. Explain by
drawing the circuit diagram, how a post-office-box is used in the laboratory to determine the resistance of a coil of wire accurately (to two places of decimal).Also mention the principle on which it is based. (3)
Q.19. A current is
flowing through a straight , thin metallic wire of infinite length .
Obtain an expression for the magnetic field at a distance from it and give its direction.(3)
Q.20. A bar magnet held
horizontally is set into angular oscillations in Earth's magnetic
field. It has time periods T1 and T2 at two places,where the angles of dip are 2 respectively. Deduce an expression for the d1 and dratio of resulting magnetic fields at the two locations.(3)
Q.21. Two sources of
monochromatic, coherent light individually produce , on a distant
screen , intensities I1
and I2 respectively. Obtain an expression for
the ratio : Imax / Imin when the two beams are allowed to fall on the screen. What would be observed on the screen if two sodium lamps are used as sources.(3)
Q.22. Light of
wavelength 5000 A falls on a metal surface of work function 1.9eV.
Find :
(a) the energy of a photon in eV.
(b) the maximum KE of photo electrons, and
(c) the stopping potential.(3)
Q.23. (a) Sketch input and
output characteristic of a transistor in CE configuration.
(b) Draw a
ckt-diagram, showing how a p-n-p transistor is used as an amplifier.(3)
Q.24.(a) Write the truth
table and give the symbol of a NAND gate.
(b) Give a
ckt-diagram to show how OR gate is realised in practice.(3)
Q.25. Using
Kirchboff's laws in the given network . Calculate the values
of I1 , I2 and I3.
(3)
Q.26. Explain with the help
of a labelled diagram for the principle, construction and working of
an ac generator. (5)
OR
Figure shows
a series LCR circuit connected to a variable frequency 220 V source
:
L=4.0
H
C=100µF
and R=40
