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Physics
Class- XII
2000(CBSE)
You are on Set no 3 Qno. 1 to
30
Time allowed : 3 hours
Maximum
Marks : 70
General Instructions :
(i) All questions are
compulsory.
(ii) Marks for each question are indicated against
it.
(iii) Question number 1 to 8 are very short-answer questions each
of 1 mark. Answer them in about one sentence each.
(iv) Question number
9 to 18 are short-answer questions of 2 marks. Answer them in not more
than 30 words each.
(v) Question number 19 to 27 are short-answer
questions of 3 marks. Answer them in not more than 50 words each.
(vi)
Question number 28 to 30 are long-answer questions of 5 marks each. Answer
to these questions should be around 150 words each.
(vii) Use Log
Tables, if necessary.
(viii) Please write down the serial number of the
question before attempting it.
Q6) Name the electromagnetic
radiation which has the largest penetrating power. (Marks
1)
Q7) Two planets A and B have
solar constants 50 W/m2 and 1400 W/m2 respectively.
Which one of the two planets has a higher temperature ? (Marks
1)
Q8) What is the polarising
angle of a medium in which the angle of refraction is 33o
? (Marks 1)
Q10) Briefly explain how the
distance of a superior planet can be determined from earth.
(Marks 2)
Q13) Four capacitors are
connected as shown in the figure given below :
Calculate the equivalent
capacitance between the points X and Y. (Marks 2)
Q14) Explain with reason, why
: (i) sun appears reddish at sunset or sunrise and (ii) sun is observed
earlier to the actual sunrise. (Marks 2)
Q22) A short bar magnet of
magnetic moment 0.9 joule/tesla, is placed with its axis at 60o
to a uniform magnetic field. It experiences a torque of 0.063 joule : (i)
Calculate the strength of the magnetic field, and (ii) what orientation of
the bar magnet corresponds to its equilibrium position in the magnetic
field ? (Marks 3)
Q27) A copper voltmeter is in
series with a heater coil of resistance 0.3 ohm. A steady current flows in
the circuit for 30 minutes. A mass of 0.99 g of copper is deposited at the
cathode. If the electro-chemical equivalent of copper is 0.00033
g/coulomb, calculate the heat generated in the coil. (Marks
3)
Q28) For a given a.c circuit,
distinguish between resistance, reactance and impedance. A resistor, a
capacitor of 100  F capacitance and a inductor are in series with an a.c. source of
frequency 50 hertz. If the current in the circuit is in phase with the
voltage, calculate the inductance of the inductor used. (Marks
3+2)
Q29) State the postulates of
Bohr's model of hydrogen atom. The electron in a given Bohr orbit has a
total energy of -3.4 e V. Calculate its : (i) kinetic energy, (ii)
potential energy, and (iii) wavelength of the light emitted, if an
electron makes a transition to the ground state. (Ground state energy =
-13.6 e V) (Marks 5)
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