A Zener of power rating 1 W is to be used as a voltage regulator. If zener has a breakdown of 5V and it has to regulate voltage which fluctuated between 3V and 7V, what should be the value of Rs for safe operation (Fig.14.12)?



Zener power rating is 1 w.


Break down voltage is given to be 5v.


So, maximum current equation is,





So, to operate safely it should control the current when it reaches the maximum value of fluctuating value.


current through Rs will be,



Hence the value of Rs will be,



=10 ohms


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