Alternating current and Alternating EMF

• An alternating current is one whose magnitude changes sinusoidal with time .Thus alternating current is given by
  
  
  Where,
  i₀=current amplitude or peak value of alternating current
  If T is the time period of alternating current and f is the frequency, then
  
  
  Where ω is called angular frequency of A.C and φ is known as phase constant
  
• Instead of sine function AC can also be represented by cosine function and both representation leads to same results. We will discuss circuits with sine representation of A.C
  
• Figure below shows the variation of A.C with time
  
  
• Complete set of variations of the current in one time period T is called cycle
  
• The emf or voltage whose magnitude changes sinusoidal with time is known as alternating emf and is represented by
  
  
  where V₀ is the peak value of alternating current.