For bidden gap for insulators is

Options

A. `ge 6eV`
B. `le 1eV`
C. `le 3eV`
D. `~= 0 eV`

Answer

To determine the forbidden gap for insulators, we need to understand the concept of energy bands in solids. Here’s a step-by-step solution:

### Step 1: Understand the Energy Bands
In solids, electrons occupy energy levels that are grouped into bands. The two most important bands are the valence band (filled with electrons) and the conduction band (where electrons can move freely and conduct electricity).

### Step 2: Define the Forbidden Gap
The forbidden gap (or band gap) is the energy difference between the top of the valence band and the bottom of the conduction band. It determines how easily electrons can be excited from the valence band to the conduction band.

### Step 3: Compare Conductors, Semiconductors, and Insulators
- **Conductors**: Have overlapping bands, resulting in no forbidden gap (0 eV).
- **Semiconductors**: Have a small forbidden gap (typically around 1 eV to 3 eV).
- **Insulators**: Have a larger forbidden gap, typically greater than 3 eV.

### Step 4: Identify the Forbidden Gap for Insulators
For insulators, the forbidden gap is usually greater than 3 eV, and it can be around 5 eV or even higher. This large gap prevents electrons from moving to the conduction band under normal conditions, making insulators poor conductors of electricity.

### Step 5: Conclusion
Thus, the forbidden gap for insulators is generally greater than 3 eV, often around 5 eV or more.

### Final Answer
The forbidden gap for insulators is greater than 3 eV.

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