11) How many two way switches are required to control one lamp from 3 different places?

12) What is the name of wiring if one lamp controlled from two different places?

13) Which diagram informs the reader about design of circuit without giving any information on the circuit itself?

14) Which diagram indicates the physical position of accessories and final appearance of Installation?

15) Which wiring circuit needs to switch ON a lamp ahead, while the light behind is put OFF?