Saturday, 14 November 2020

How Ideal Diode is work??

  • IDEAL DIODE:-


Fig(a) Symbol of Diode

⇒An ideal diode is behaves same as an Ideal switch.

  • Behaviour of an Ideal Switch:
         CASE:-1  When Switch SW is Open;


➝" An ideal switch is defined as a device which doesn't consume any power from the supply source".


➝When switch is open then current trough the switch Isw = 0 amp. Because source is isolated from the load RL.

  • At that time voltage across the sitch sw (Vsw) is ..............
  •  Applying KVL........

          -Vs + Vsw + VL = 0 .............(1)


But, switch SW is open so current Isw=IL = 0 

            VL = IL × RL 

         ∴ VL = 0 × RL

            VL = 0 volt ................(2)

Put VL= 0 in Equation Number (1).......


               -Vs + Vsw + 0 = 0 

            ∴ Vs = Vsw ..............(3)


  • Power loss across the switch SW during switch SW is open is (P1).........
                 P1 = Isw × Vsw

                       =  0 × Vsw

                   P1 = 0 watt.


     CASE:-2 When Switch SW is closed



➝ When Switch SW is closed then the voltage across it Vsw = 0, because of short circuit. But the current Isw= IL ≠ 0.

  • Power loss across the switch SW during switch SW is closed is (P2)..........

                P2 = IL × Vsw

                     = IL × 0 

                 P2 = 0 watt.


So, from above discussion we conclude that an Ideal switch SW doesn't consume any power from the source.


  • I-V characteristics of an Ideal Diode:


➝ During positive half cycle of ac supply ,When Switch SW is closed at that time Vsw=0 and I >0 so the Characteristic is straight line (vertical) passing through origin as shown in I-V characteristics.

➝During the negative half cycle of ac supply, when switch SW is open at that time Vsw>0 and I= 0 so the Characteristic is straight line (Horizontal) passing through the origin as shown in I-V characteristics.

➝In above both cases R= 0 because it is an Ideal Diode.



           ....................Thank you 🙂..................





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