11. What is meant by Complex power? 12. What are the advantages of 3 phase circuits over single phase circuits? 13. State the relationship between line voltage & phase voltage and line current & phase current of a 3 phase delta connected system. 14. State the relationship between line voltage & phase voltage and line current & phase current of a 3 phase star connected system. 15. Write the expression for the instantaneous values of emfs in a 3 phase circuit.