Short Answer Typea) In a typical nuclear reaction, e.g. , 
Although number of nucleons is conserved, yet energy is released. How? Explain.
b) Show that nuclear density in a given nucleus is independent of mass number A.a)
In a nuclear reaction,
In a nuclear reaction, the sum of the masses of the of the target nucleus and the bombarding particle may be greater or less than the sum of masses of the product nucleus and the outgoing particle. Therefore, from the law of conservation of mass-energy around 3.27 MeV is evolved or involved in a nuclear reaction. This energy is called the Q-value of the nuclear reaction.
Cause of the energy released:
i) Binding energy per nucleon of becomes more than the BE/A of 
ii) Mass defect between the reactant and the product nuclei.
b) The radius of nucleus of mass number A is given by R = 
Volume of the nucleus, 
Density of the matter in the nucleus is given by,
Hence, density is independent of mass number A.
(a) Why photoelectric effect cannot be explained on the basis of wave nature of light? Give reasons.
(b) Write the basis features of photon picture of electromagnetic radiation on which Einstein’s photoelectric equation is based.Output characteristics of an n-p-n transistor in CE configuration is shown in the figure. Determine:
(a) Dynamic output resistance
(b) DC current gain and
(c) AC current gain at an operating point VCE=10V, when IB=30
A. 
Using Bohr’s postulates, obtain the expression for the total energy of the electron in the stationary states of the hydrogen atom. Hence draw the energy level diagram showing how the line spectra corresponding to Balmer series occur due to transition between energy levels.
(a) In what way is diffraction from each slit related to the interference pattern in a double slit experiment?
(b) Two wavelength of sodium light 590 nm and 596 nm are used, in turn, to study the diffraction taking place at a single slit of aperture 2 x 10-4 m. The distance between the slit and the screen is 1.5.m. Calculate the separation between the positions of the first maxima of the diffraction pattern obtained in the two cases.
Long Answer TypeWhile travelling back to his residence in the car, Dr. Pathak was caught up in a thunderstorm. It became very dark. He stopped driving the car and waited for thunderstorm to stop. Suddenly he noticed a child walking alone on the road. He asked the boy at his residence. The boy insisted that Dr. Pathak should meet his parents. The parents expressed their gratitude to Dr. Pathak for his concern for safety of the child.
Answer the following questions based on the above information:
(a) Why is it safer to sit inside a car during a thunderstorm?
(b) Which two values are displayed by Dr. Pathak in his actions?
(c) Which values are reflected in parents’ response to Dr. Pathak?
(d) Give an example of a similar action on your part in the past from everyday life.
(a) State the working principle of a potentiometer. With the help of the circuit diagram; explain how a potentiometer is used to compare the emf’s of two primary cells. Obtain the required expression used for comparing the emf’s.
(b) Write two possible causes for one sided deflection in a potentiometer experiment.
OR
(a) State Kirchhoff’s rules for an electric network. Using Kirchhoff’s rules, obtain the balance condition in terms of the resistances of four arms of Wheatstone bridge.
(b) In the meter bridge experimental set up, shown in the figure, the null point ’D’ is obtained at a distance of 40 cm from end A of the meter bridge wire. If a resistance of 10W is connected in series with R1, null point is obtained at AD=60 cm. Calculated the values of R1 and R2.
(a) Derive the expression for the torque on a rectangular current carrying loop suspended in a uniform magnetic field.
(b) A proton and a deuteron having equal momenta enter in a region of uniform magnetic field at right angle to the direction of the field. Depict their trajectories in the field.
OR
(a) A small compass needle of magnetic moment ‘m’ is free to turn about an axis perpendicular to the direction of uniform magnetic field ‘B’. The moment of inertia of the needle about the axis is ‘I’. The needle is slightly disturbed from its stable position and then released. Prove that it executes simple harmonic motion. Hence deduce the expression for its time period.
(b) A compass needle, free to turn in a vertical plane orients itself with its axis vertical at a certain place on the earth.
Find out the values of
(i) horizontal component of earth’s magnetic field and
(ii) angle of dip at the place.
(a) Draw a ray diagram showing the image formation by a compound microscope.
Hence obtain expression for total magnification when the image is formed at infinity.
(b) Distinguish between myopia and hypermetropia. Show diagrammatically how these defects can be corrected.
OR
State Huygens principle. Using this principle draw a diagram to show how a plane wave front incident at the interface of the two media gets refracted when it propagates from a rarer to a denser medium. Hence verify Snell’s law of refraction.
(b) When monochromatic light travels from a rarer to a denser medium, explain the following, giving reasons:
(i) Is the frequency of reflected and reflected light same as the frequency of incident light?
(ii) Does the decrease in speed imply a reduction in the energy carried by light wave?
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