1. Draw a schematic ray diagram of a compound microscope when image is formed at distance of distinct vision.
2. Write the expression for resolving power of a compound microscope. How can the resolving power of a microscope be increased?

1. What are the three basic units in communication systems? Write briefly the function of each of these.
2. Write any three applications of the internet used in communication systems.

1. Define the term ‘intensity of radiation’ in terms of photon picture of light.
2. Two monochromatic beams, one red and the other blue, have the same intensity. In which case (i) The number of photons per unit area per second is larger, (ii) The maximum kinetic energy of the photoelectrons is more? Justify your answer.

State the principle of a cyclotron. Show that the time period of revolution of particles in a cyclotron is independent of their speeds. Why is this property necessary for the operation of a cyclotron?

1. Write the important properties of photons which are used to establish Einstein’s photoelectric equation.
2. Use this equation to explain the concept of (i) threshold frequency and, (ii) Stopping potential.

A series LCR circuit is connected to an ac source. Using the phasor diagram, derive the expression for the impedance of the circuit. Plot a graph to show the variation of current with frequency of the source, explaining the nature of its variation.

Define the electric resistivity of a conductor.
Plot a graph showing the variation of resistivity with temperature in the case of a (a) conductor, (b) semiconductor.
Briefly, explain, how the difference in the behaviour of the two can be explained in terms of number density of charge carriers and relaxation time.

Find the electric field intensity due to a uniformly charged spherical shell at a point (i) outside the shell and (ii) inside the shell. Plot the graph of electric field with distance from the centre of the shell.