The energy gap in case of which of the following is less than 3 eV?

Options

A. Germanium
B. Iron
C. Copper
D. Aluminium

Answer

To solve the question regarding which material has an energy gap of less than 3 eV, we can follow these steps:

### Step 1: Understand the Concept of Energy Gap
The energy gap (or band gap) is the energy difference between the top of the valence band and the bottom of the conduction band in a semiconductor. This gap determines the electrical conductivity of the material.

### Step 2: Identify the Energy Gaps of Common Materials
We need to know the energy gaps for the materials mentioned in the question. Here are some common values:
- **Germanium (Ge)**: Approximately 0.67 eV
- **Silicon (Si)**: Approximately 1.1 eV
- **Copper (Cu)**: As a metal, it does not have a band gap in the same sense as semiconductors, but it conducts electricity very well.
- **Iron (Fe)**: Similar to copper, iron is a metal and does not have a defined band gap.
- **Aluminum (Al)**: Also a metal with no band gap.

### Step 3: Compare the Energy Gaps
Now we compare the energy gaps:
- Germanium: 0.67 eV (less than 3 eV)
- Silicon: 1.1 eV (less than 3 eV)
- Copper: No band gap (not applicable)
- Iron: No band gap (not applicable)
- Aluminum: No band gap (not applicable)

### Step 4: Conclusion
From the above comparisons, we can conclude that both Germanium and Silicon have energy gaps that are less than 3 eV. However, since the question asks for which of the following is less than 3 eV, the most relevant answer is **Germanium**, which has a specific value of 0.67 eV.

### Final Answer
The energy gap in the case of **Germanium** is less than 3 eV.

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