<p>The VI characteristics curve of a PN junction diode is shown.</p>

<p><img alt="" src="https://school.achievam.com/upload/questionbank/question/que_1758513861.jpg" style="height:200px; width:278px" /></p>

<p>(a) Identify the region corresponding to forward bias and reverse bias.<br />
(b) Mark the threshold voltage on the graph.<br />
(c) Explain why the current rises sharply after the threshold voltage in forward bias.</p>