expand M.C.B and C.F.L ? write their importances ?

MCB stands for Miniature Circuit Breaker. They are safety switches used for protection of appliances and human beings. If the current through a circuit exceeds the safety limits rated by the MCB, it automatically turns off and protects the devices connected to the circuit. MCBs are the replacement for safety fuses which were used in earlier.

CFL stands for compact fluorescent lamps. The main advantage is the energy efficiency. It is considered to be green technology as they consume less electricity as compared to normal incandescent lamps or other kind of lamps.