i just studied about the SCR halfwave rectifier .
but how can the load be connected before the SCR.
does it make any sense of rectification...........

 

Show us a schematic and we might be able to help. Electronics is very visual, and a picture will clear up confusions.

 

here' the circuit. pls explain

 

The SCR only permits the negative half cycle to push current into the battery.

 

Same person? Or same course?

You'll also find SCRs used in DC regulators (usually switching) as crowbar circuits. They short the entire power supply if the regulation fails. The reason is they can be feeding some very expensive electronics (think $10K or more) and the power supply, while expensive, is the cheap part.

 

And they can also be used as regulators by modulating the firing angle, then following the rectifiers with a low pass filter. Great way to regulate thousands of watts, but may not be convenient for smaller applications.