(i) Some I represents direct current (DC) whereas source II represents alternating current (AC).
(ii) Source I may be a dry cell or a Voltaic cell and Source II is an AC Generator.
(iii) The period (T) of AC (Source II) is `0*03s-0*01s=0*02s`. Thus, the frequency of AC, i.e., `v=1/T=(0)/(0*02s)=50Hz`.
(iv) (a) The magnetude of DC remains the constant whereas that of AC keeps on changing.
(b) The direction of DC remains the same whereas that of AC keeps on changing.