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Q1. Express London equation assuming a superconductor in DC field. Find an expression of field penetration in a superconductor placed in an AC field. Explain the different causes of field penetration. Derive Gibb's free energy relation between normal metal and superconductor in terms of critical magnetic field. Show that entropy in Superconducting state is lower than normal state. Q2. What is Meissner effect? Find an expression of Penetration Depth in a superconductor? Clearly distinguish Type I and Type II superconductor. Give example of two high Tc superconductors? What is Cooper pair? What is the origin of energy gap associated with a superconductor? Q3. What is meant by Single Particle Tunnelling? What is Josephson's Tunnelling? Explain DC Josephson effect and find an expression of current density? Also explain AC Josephson effect and hence find the current density in this case? How can you determine precisely the value of e/ h. Q4. Find an expression for the local field that is responsible for polarizing atoms in a solid? Calculate the dipolar polarizability of a dipolar system at temperatures that are not too low and the fields are not too large. Explain ionic polarizability and find an expression of dielectric constant when an alternating field is applied to the ionic crystal. Describe the principle of measuring dielectric constant of a specimen applying resonance method.