HSC Physics- 2nd
Paper (Theo) Model Question for Class- XII
1 a. What
is point charge? Derive the equation for
the capacitance of a parallel plate capacitor. 1+4=
5
b. What is electrolysis? State
and explain Faraday’s laws of electrolysis 6
c. The length of a meter bridge wire is 1m. A standard resistor of 12Ω.
is placed in its left gap
and an unknown
resistor is placed on the right gap. A
null point is found at 37.5cm from
the end. Calculate the unknown
resistance.
4
Or,
a. State the laws of resistance and from it define specific
resistance. 5
b What is inversion temperature? How can the resistance of a wire be
measured by a meter
bridge?- Explain.
1+5= 6
c.
Which one will use more energy- a television of 250watt used for 1hr. or
an electric iron of 1
200watt. used
for 10 min.? 4
2. a. Define conjugate foci. For
a thin spherical lens prove that,
1+5= 6
1+5= 6
here the
symbols refer their traditional meaning.
b By drawing rays of path describe the working principle of a
compound microscope and derive
the equation
of its magnification. 5
c. A person having defective vision cannot see object beyond 5m.and
cannot see object less
than a
distance of 0.5m. Lenses of what power are to be used to see object at long
distance
and for
reading. 4
Or,
a. Define critical angle. Show that the refractive index of the
denser medium with respect to the
rarer medium
is equal to the inverse of the critical angle between them. 1+5= 6
b Establish the relation between refractive index, actual depth and
apparent depth if the object is
in the denser
medium. 5
c In front of a concave mirror of focal length of f an object at a
distance of 3f from the mirror.
Show that the
size of the image will be half of the size of the object. 4
3. a What is LASER? Discuss the failures of classical mechanics in
explaining the black body
radiation. 1+5= 6
b. Show that N= N
e-
where the symbols have
their usual meaning. 5
e- where the symbols have
their usual meaning. 5
c In a common base transistor the collect current is 0.85mA. and the
base current is 0.05mA.
Calculate
current amplification factor. 4
Or,
a. Derive the equation for
the radius of electron of hydrogen atom according to Bohr’s atom model. 6
b. Draw a circuit diagram
for a full wave rectifier and describe its working principal. 5
c. If the total energy of a
moving particle is 2.5 times the stationary energy. What is the speed
of the particle? 4
4. Prove that the energy
stored per unit volume at a point inside a capacitor, U=
5
5
Or,
a Mention
the fundamental postulates of Bohr’s atom 3
b. Prove that the equivalent capacitance
of 4 capacitors of equal values when connected in series
is 1/16 times
the equivalent capacitance when connected in parallel. 2
5. Describe the electrical
method for the determination of mechanical equivalent of heat by
Joule’s
Calorimeter. 5
Or,
What is
Peltier effect? If the electro chemical equivalent of silver is 1.118×10-6kg.C-1.
and atomic mass of silver is 108.
Calculate the E.C.E. of Hydrogen. 1+4= 5
6. Show that the flux density at a nearby
point of a long wire carrying current, B =
1+4= 5
1+4= 5
Or,
a. What is called Tesla? 1
b. The diameter of a circular coil is 31.4×10-2m and its
number of terns is 400. For what amount of current
flow in the coil, the magnetic field at
the centre of the coil will be 4×10-10wb.m-2 4
7. What
is light year? In Fizeau’s experiment the velocity of light was found 3×108m.s-1
. if the number of the teeth of the wheel was 720 and frequency 10.8 Hz.
Find the distance between the wheel and the mirror. 1+4
= 5
Or,
a. For a thin prism show that the
deviation, 
A, where the symbols
have their usual
A, where the symbols
have their usual
meaning. 2
b. A convex lens of focal length of 0.25m.
is in contact with a concave lens of focal length of 0.75m.
Determine the equivalent focal length
of the combination. 3
8. Prove that, m =
5
5
Or
,
a. What are the postulates of special
theory of relativity? 2
b. If an electron moves with .99C
speed. Find its moving mass. 3
9. Establish the mass-energy equation of
Einstein. 5
Or,
a. What is plasma state? 1
b. The decay constant of radioactive
substance is 3.75×10
s
. Calculate the half life. 4
s. Calculate the half life. 4
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