Time : 3 hrs. Marks.
75
1. a) State Kirchhoffi's two laws. Establish,
Wheatstones' Bridge principle by kirchhoffi's laws.1+5
b) Find an expression for electric
potential at a distance r, from a point change +Q. 5
c) A Wheatstone bridge has resistances to
three arms are 25W,
20W
and 30W
respectively. When
10W is
joined in series to the 4th arm of the bridge, then the bridge is balanced.
Find the initial
resistance
at 4th arm. 4
Or, a) Derive an expression for magnetic force
on a current carrying conductor in a magnetic field. 5
b) What is dip circle? Describe how dip of
a place can be determined by it. 1+5
c) On the surface of an electric bulb 220V
and 100W is written. Determine the resistance of
the wire of
the bulb and when it is joined to a supply of 220V, determine also its power. 4
2. a) Proof of the condition of for minimum
deviation. 6
b) In case of spherical mirror, Prove
the f = 
. 5
. 5
c) The refractive index of red light is
1.42 for a thin prism and the refracting angle is 100.
find the
deviation of the red light. 4
Or, a) What is wave front? Proof of laws
refraction by H/g Huygen's principle ( on the basis of
wave
theory). 1+5
b) In case of spherical refracting
surface, prove that, 
. 5
. 5
c) The number of lines of a plane
diffracting grating per cm is 4200. If the angle of 2nd diffracting is 300, Find the wave length. 4
3. a) What do you mean by contraction of
length? prove that L = Lo 
. 1+5
. 1+5
b) What is LASER? State the
characteristics of LASER. 1+4
c) A ray of untravialet light of
wavelength 3000 A0 falling on
the surface of a material,
whose work
function is 3.62 x 10-19 j, ejects an
electron. What will be the velocity of the emilted electron? 4
Or, a) Explain mean life, Fission and fusion. 6
b) Describe p -n- p transistor. 5
c) How much energy will be obtained when a
body of mass 1 kg is completely transformed to
energy.
Express the result in Mev unit. 4
4. Describe the
determination of the mechanical equivalent of heat. 5
Or What is
faraday? Show that when two capacitors of equal capacitance are connected in
parallel.
the
equivalent capacitance will be 4 times to that of when they are connected in
series. 1+4
5. Describe the
construction and working principle of transformer. 5
Or What is
shunt? Describe how the range of a ammeter is increased by using a shunt. 1+4
6. What is Hall
effect? Derive an expression of Hall vallage. 1+4
Or, What is metre
bridge? Describe how the resistance is determined by metre bridge. 1+4
7. What is
critical angle? An object is placed at a distance of x from a concave mirror of
radius
of
curvature r. Show that image distance = 
. 1+4
. 1+4
Or, What is
differaction grating? At what distance from a convex lens of focal length 1.4 m
should
be an
object placed so that a real image of 
times magnified will
produce? 1+4
times magnified will
produce? 1+4
8. Describe the
construction and principle of action of a compound microscope. 5
Or, What is
magnetic flux? The radius of a circular coil is 3.14 x 10-2 m and the
number of turns is
100. Find
the quantity of charge that flowed through the coil so that the magnetic flux
produced at
the centre
is 8x10-10
T,
9. What is
Threshold Frequency? Find the velocity of an electron form its rest position
when a potential difference of
5 Kv is applied. 1+4
Or, What is
radioactivity? If the half life of radon is 6.93 day, how many days will 
th of a radon atom sample remain behind? 1+4
th of a radon atom sample remain behind? 1+4
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