Chapter 29, Problem 45A

To determine

The functioning of an ohmmeter with a diode in the circuit.

Explanation of Solution

Introduction:

An ohmmeter is a device used to measure the resistance of the circuit between the terminals of the meter. A diode is a semiconductor device which allows current to pass through only in one direction.

An ohmmeter measures the resistance by applying a small external voltage across the device, measures the resulting current and calculates the resistance. A diode allows current to pass through only in one direction. Therefore, if the positive end of the ohmmeter is connected to the negative end of the diode, the diode will not allow any current to flow and hence, the ohmmeter will measure infinite resistance. This circuit is called biased state. To allow current through the circuit the connection must be forward biased.

Conclusion:

To allow current through the circuit, the connection must be forward biased.