current or voltage we measure for AC are alaways rms(root mean square) value not the actual magnitude so 220 volt ac(rms)= 220*sqrt(2)=311 volt but 220 volt DC alaways gives the magnitude...
To score good in your board examinations , there is always need of hard work but along with this students also require smart work, this helps students in laerning and understanding capability in a short...