Root mean square Alternating Current or rms current:

 

 

1) Also known as r.m.s value of current.


2) The amount of direct current (I rms) which produces same amount of heat as it is produced by alternating current for same interval of time is called r.m.s  current.

 


3) That is

 

 Then that amount of Direct Current is called r.m.s  current.




4) We know

Power 



Therefore


Now current    


but we know that 







therefore work done in one complete cycle is












This work is done by alternating current.

 

Now for direct current



Now according to r.m.s  value definition

7.23 & 7.32 are equal, So

 


 






Similarly we can also define r.m.s  voltage