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SAMPLE PAPER
PHYSICS
SET-III
Time Allowed : 3 Hours
Maximum Marls : 70
General Instructions :
(i) All questions are compulsory.
(ii) Marks for each question are indicated against it.
(iii) Question numbers 1 to 8 are very short-answer
questions, carrying 1 mark each. There are to be answered in one or two
sentences.
(iv) Question numbers 9 to 18 are short - answer questions,
each carrying 2 marks. Answer to these questions should be around 30 words each.
(v) Question numbers 19 to 27 are also short-answer
questions, each carrying 3 marks. Answer to these questions should be around 50
words each.
(vi) Question numbers 28 to 30 are long-answer questions,
each carrying 5 marks. answer to these should be around 150 words.
(vii) Use log tables, if necessary. |
| Q.1. |
Is electric flux a scalar or a vector quantity
? Write its S.I. unit. |
| Q.2. |
Name the wave phenomenon which is exhibited by
light waves but not by the sound waves. |
| Q.3 |
Two stars A and B have magnitudes of -2 and e
respectively. which of the two is brighter and by how much ? |
| Q.4. |
Will the drift speec of free electrons is a
metalic conductor increase or decrease with the increase in its temperature ? |
| Q.5. |
A magnetic needle free to rotate in a vertical
plane orients itself with its axis vertical at a certain place on the earth. What
are the valves of (a) horizontal component
of earth's magnetic field
(b) Angle of dip at this place. |
| Q.6. |
Name the waves used in RADAR and write the
order of their wavelength. |
| Q.7. |
A steady current flows in a metallic conductor
of non uniform cross section. which of the following quantities is are constant
along the conductor current, current density, drift speed. |
| Q.8. |
The variation of P.d. with length in case of
two potentiometers A and B is given below. Which of the two is more sensitive. |
| Q.9. |
State Kirchoff's Laws for an electric network.
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| Q.10. |
What is meant by the term 'interference of
light' Write any two conditions necessary for obtaining well defined and sustained
interference pattern of light. |
| Q.11. |
Define the term angular dispersion. Draw
the path of ray of white light paspsing through a prism and mark angular dispersion on it.
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| Q.12. |
The radius of curvature of each surface of a
Convex lens of refractive index 1.5 in 40cm. calculate its power. |
| Q.13. |
Obtain the relation between the frequency of
revolution of a planet and its orbital radius. |
| Q.14. |
A sphere S1 of radius r1 encloses a total
charge Q. If there is another concentric sphere S2 of radius r2 (r2 > r1) and there be
no additional charges between S1 and S2. Find the ratio of elecltric flux through S1
and S2. |
| Q.15. |
A simple voltaic cell has an emf of IV.
Is there a net field inside the cell when (1) circuit is open (ii) circuit is
closed and a steady current is drawn from it. Explain your answer in each case. |
| Q.16. |
Suppose a helical spring is suspended from the
roof of a room and very small weight is attacked to its lower end. what will happen
to the spring when a current is passed through it. give reason to support your
answer. |
| Q.17. |
A charged oil drop falls under gravity with a
terminal speed V. the drop is held stationary by applying suitable elecltric field
in a Millikan's set up and is found to carry 2 excess electrons. Suddenly the drop
is observed to move upward with the same velocity v. why does the drop move upward ?
write relevant mathematical equations in support of your answer. |
| Q.18. |
If the emitter and base of a npn transistor
have same doping concentration, then explain how will the collector and base currents be
affected ? |
| Q.19. |
What is Seeback effect ? Draw a curve to show
the variation of thermo emf with the gradual increase in the temperature of hot junction.
Mark the neutral temperature and temperature of inversion of the thermocouple on
the curve. |
| Q.20. |
Draw the logic symbol and write the truth
table of AND gate. With the help of a circuit diagram describe the realisation of
AND gate using semiconductor diodes. |
| Q.21. |
What is meant by the current sensitivity of a
moving coil galvanometer ? On what factors does it depend ? In an exercise to increase
current sensitivity of a galvanometer by 25 % its resistance is also increased by 1.5
times. how will the voltage sensitivity of the meter be affected ? |
| Q.22. |
An electron beam of initial energy 18 key
moving horizontally is subjected to a horizontal magnetic field of 0.4 G normal to the
initial direction. Calculate the vertical deflection of the bean over a distance of
30 cm. |
| Q.23. |
When 100 VDC is applied across an inductor a
current of 1A flows through it. If the same inductor is connected to a 100 V
AC source, the current reduces to 0.5. Why is the current reduced in the later case
? Callculate the valves of the reactance of the inductor. |
| Q.24. |
Monochromatic light of wavelength 589 nm is
incident from air on a water surface. what are the valves of wavelength, frequency
and speed of (a) reflected light (b)
refracted light
refractive index of water in 1.33 |
| Q.25 |
Two electric bulbs of 50 and 100 watts are
given. Which one of the two will be brighter when they are connected to mains (a) in
series (b) in parallel. |
| Q.26. |
With the help of a circuit diagram explain the
use of npn transistor as an amplifier in common emitter configuration. What is the
phase relationship between collector and base voltages ? |
| Q.27. |
Using the data given below state which two of
the given lenses will you prefer to construct a best possible (i) telescope (ii)
microscope. Also indicate which of the seleclted lenses is to be used an as objective and
as an eyepiece in each case. |
| Q.28. |
State Postulates of Bohr's atomic model.
Derive an expression for the total energy of an electron in nrh oebir. |
| Q.29. |
A parallel plate capacitor with air between
its plates having plate area of 6 x 10-3 m2 and separation between them 3 mm is connected
to a 100 v supply. Calculate charge on each plate of the capacitor. Explain
what would happen when a 3 mm thick mica sheet (dielectric constant =6) is inserted
between the plates. (a) While the voltage
supply remains connected.
(b) after the supply is disconnected. |
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or |
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Derive an expression for the energy stored in
capacitor of capacitance 'C' when it is charged by connecting it to a battery of p.d. 'V'.
Now if the capacitor is disconnected from the battery. What will be the energy
stored in the capacitor when (i) separation between plates is double and (ii) an uncharged
and identical capacitor is connected across is. |
| Q.30. |
A small town with a demand of 880 kw of
electric power at 220 V is situated 15 km away from an electric plant generating power at
440 V. the resistance of the cable carrying power is 15 Ohm. the town gets
power through a 4400 - 220 V step down transformer at a sub-station in the town. (a) Calculate the line power loss in the form of heat.
(b) How much power must the plant supply, assuming there is
a negligible power loss due to leakage.
(c) Calculate the voltage drop in the line. |
