Chapter 29, Problem 64A

To determine

Whether an ohmmeter shows a high resistance for a forward biased or reverse biased diode.

Explanation of Solution

Introduction:

When a potential difference of the proper polarity(positive terminal of the battery is connected to the n-type semiconductor material and the p-type material is connected to the negative terminal) is applied across a p-n junction diode, it makes the depletion layer even wider, no current is observed, and the diode is said to be reverse biased.

Reversing the polarity of the applied potential across the diode greatly decreases the depletion layer, current flows, and the diode is forward biased.

In forward biased mode, the positive terminal of the supply is in connectionwith the p-type material and negative terminal with the n-type. Forward bias decreases the potential barrier by decreasing the depletion layer and creates the easy path for flow of current.

Whereas, in reverse biased mode, the positive terminal of the supply is in connection with the n-type semiconductor material and the p-type material is in connection with the negative terminal. In reverse bias, the potential difference rises barrier’s strength across the junction. It provides a high resistive path to the flow of current due to which very less or no current flows through the circuit.

Hence, an ohmmeter will show a high resistance for a reverse-biased diode.

Conclusion:

An ohmmeter will show a high resistance for a reverse-biased diode.