Direct current means that the polarity of the e.m.f remains constant with time.
- Current flows only in one direction, hence charge carriers flow in one direction only.
Types of direct current waveforms:
Alternating current means that the polarity of the e.m.f. changes with time.
- Direction of current flow in the electrical circuits varies with time in a periodic manner.
- Direction of the charge carriers’ flow changes back and forth.
Types of alternating current waveforms:
Features Of An A.C. Waveform
The sinusoidal alternating current can be represented by $I = I_{o} \, sin \, \omega t$
For a I vs T graph,
- A cycle refers to one complete alternation of $I$
- Period T refers to the time taken to complete one cycle of variation
- Frequency f is the number of complete cycles of variation in one second
- Instantaneous current refers to the current value at an instant of time.
- Peak current value $I_{o}$ refers to the maximum current during the cycle or the amplitude of the a.c. signal.
- Peak to peak value is the difference between the positive and negative $I_{o}$ value. For sinusoidal a.c., the peak to peak value is 2 $I_{o}$.
