Which of the following statement is wrong regarding a p - n junction diode

Options

A. Diode may illuminate light
B. Diodes are rectifying devices
C. Diodes are unidirectional devices
D. Diodes have three terminals

Answer

To determine which statement is wrong regarding a p-n junction diode, let's analyze each option step by step.

### Step 1: Understand the structure of a p-n junction diode
A p-n junction diode consists of two types of semiconductor materials: p-type and n-type. The p-type semiconductor has an abundance of holes (positive charge carriers), while the n-type semiconductor has an abundance of electrons (negative charge carriers). The junction between these two materials creates a diode.

**Hint:** Remember that a p-n junction diode has only two terminals: anode (p-type) and cathode (n-type).

### Step 2: Evaluate the first statement
The first statement claims that a diode may illuminate light. This is true for light-emitting diodes (LEDs), which are a type of p-n junction diode designed to emit light when current flows through them.

**Hint:** Consider the special case of diodes that emit light, like LEDs.

### Step 3: Evaluate the second statement
The second statement says that diodes are used to rectify devices. This is also true, as diodes are commonly used in rectifiers to convert alternating current (AC) to direct current (DC).

**Hint:** Think about the role of diodes in circuits, particularly in converting AC to DC.

### Step 4: Evaluate the third statement
The third statement asserts that diodes are unidirectional. This is correct; diodes allow current to flow in one direction (forward bias) and block it in the opposite direction (reverse bias).

**Hint:** Recall the concept of forward and reverse bias in diodes.

### Step 5: Evaluate the fourth statement
The fourth statement claims that a diode has three terminals. This is incorrect. A p-n junction diode has only two terminals: the anode and the cathode.

**Hint:** Remember the basic structure of a diode and how many terminals it has.

### Conclusion
Based on the analysis of each statement, the wrong statement regarding a p-n junction diode is that "a diode has three terminals." Therefore, the answer is:

**Answer:** Option 4: A diode has three terminals (This statement is wrong).