If a p-n junction diode is reverse biased, then the resistance measured by an ohm-meter will be

Options

A. zero
B. low
C. high
D. infinite

Answer

To determine the resistance measured by an ohmmeter when a p-n junction diode is reverse biased, we can follow these steps:

### Step 1: Understand the Configuration of the Diode
A p-n junction diode consists of two types of semiconductor materials: p-type (which has an abundance of holes) and n-type (which has an abundance of electrons). When the diode is reverse biased, the p-type side is connected to the negative terminal of the battery, and the n-type side is connected to the positive terminal.

**Hint:** Remember that in reverse bias, the p-side is negative and the n-side is positive.

### Step 2: Analyze the Depletion Region
In reverse bias, the applied voltage increases the width of the depletion region, which is the area around the p-n junction where mobile charge carriers are depleted. This widening of the depletion region creates a higher potential barrier that prevents current from flowing through the diode.

**Hint:** The depletion region is crucial because it determines how easily current can flow through the diode.

### Step 3: Consider the Effect on Resistance
As the potential barrier increases due to reverse bias, it becomes increasingly difficult for charge carriers to cross the junction. This leads to a very small current (ideally zero) flowing through the diode. Since resistance is defined as the ratio of voltage to current (R = V/I), if the current is negligible, the resistance becomes very high.

**Hint:** Think about Ohm's Law and how current affects resistance.

### Step 4: Conclude the Resistance Measurement
Practically, when measuring the resistance of a reverse-biased diode with an ohmmeter, the resistance will be very high, but not infinite. In an ideal scenario, we could consider it to be infinite, but in practice, it is simply high enough that it can be treated as an open circuit.

**Hint:** Consider the difference between ideal and practical scenarios in electronics.

### Final Answer
The resistance measured by an ohmmeter when a p-n junction diode is reverse biased will be **high**.