Q.1. Under what conditions a concave lens
can behave as a converging lens ? Q.2. A current carrying circular loop is
located in a uniform magnetic field. If the loop is free to turn. What is the
orientation of stable equilibrium? Q.3. How does the speed of light in glass
change on increasing the intensity of light? Q.4. Does the value of temperature
coefficient of resistance always positive? Q.5. On what factors does the colour of a
star depend? Q.6. A primary and a secondary cell have
the same e.m.f. Which of these will provide higher value of the maximum
current? Q.7. A coil' and a bulb arc connected in
series with a 6 volt d.c. source. A soft iron core is then inserted' in the
coil. What will happen to the intensity of the bulb? Q.8. A convex bus on a screen forms the
image of a candle. If the lower half of the bus in painted black to make it
completely opaque, will the full size of image be obtained? Q.9. A 4.5-cm needle placed 12 cm away from
a convex mirror of focal length 1 5 cm. Give the location of the image and
the magnification. Describe what hap- pens as the needle is moved farther
from the mirror? Q.10. What is solar constant and solar
luminosity? How their knowledge helps us to find the surface temperature of
sun? Q.11. Is any work done by a magnetic field
on a charge moving at right angles to the magnetic field? If not, how can it
deflect the particle? If so, where does the energy come from? Q.12. Two coherent sources of intensity ratio 'a' interfere. Prove that in the interference pattern |

Q.13. How does a current carrying conductor
coil behave like a magnet Q.14. How is a necessary to use satellites
for long distance T.V. transmission Why? Q.15. How is a transformer used in long
distance transmissions of a.c.? Q.16. The angle of minimum deviation for
prism of angle p /3 is p /6. Calculate the
velocity in the material of the prism if the velocity of light in vacuum is 3
x 1 0 Q.17. Find the half-life of U Q.18. The gain of a common emitter
amplifier is given by A = - gm R Q.19. Give construction of meter bridge.
How can you measure unknown resistance of wire with the help of meter bridge. Q.20. Two charges + 20 m C and -1 0m C are 20 cm apart. Calculate potential at a point P
at a distance of 1 meter from either charge. Also calculate potential energy
of a + 4m C charge placed at point P. Q.21. Discuss the formation of energy bands
in solids with one example. Q.22. A steady current of 100 ampere is
maintained in copper voltmeter. Calculate the time required to deposit 2.5 g
of copper. Relative atomic mass of copper is 63.5. Q.23. Draw a labelled diagram of Hertz
experiment for generation of electromagnetic waves. How they were detected? Q.24. Define half-life of radioactive substance. Derive an expression for it. |

Q.25. Explain with diagram forward and
reverse biasing in (i) n-p-n transistor and (ii) p-n-p transistor

Q.26. In the circuit given, calculate current
in 3 W resistor and power loss in whole circuit.

Q.27. An electron is projected with the
velocity of 10^{5} m/s at right angle to the magnetic field

Of 0.019G. Calculate radius of circle
Described by the electron.

Q.28. A conducting slab of thickness t (<
d) is placed in a parallel plate capacitor. Derive an expression for the
capacitance of the capacitor. OR

What is electric polarisation? Prove that the
resultant electric field in a dielectric when placed between the plates of
parallel plate capacitor is given by

E= Eo-(P/e o)

where E is the electric field in the absence
of dielectric and P is polarization vector.

Q.29. What is photoelectric effect? Explain
the effect of increase of (i) frequency (ii) intensity of the incident
radiation on photoelectrons emitted by a phototube.

Q.30. A variable frequency 230 V alternating
voltage source is connected across a series combination of L = 5 0 H, C = 80 m C and R = 40 W . Calculate (i) the angular frequency of source,
which derives the circuit in resonance. (ii) Amplitude of the current at
resonance frequency (iii) r.m.s potential drop across inductor at resonating frequency.