The number of atoms per unit cell in bcc lattice is

Options

A. 1
B. 2
C. 4
D. 9

Answer

To find the number of atoms per unit cell in a body-centered cubic (BCC) lattice, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the BCC Structure**:
- In a BCC lattice, there are atoms located at the corners of the cube and one atom at the center of the cube.

2. **Count the Corner Atoms**:
- There are 8 corners in a cube, and each corner atom is shared by 8 adjacent unit cells. Therefore, the contribution of each corner atom to the unit cell is \( \frac{1}{8} \).
- Total contribution from corner atoms:
\[ \text{Contribution from corner atoms} = 8 \times \frac{1}{8} = 1 \]

3. **Count the Center Atom**:
- The atom located at the center of the cube is entirely within the unit cell, contributing fully to the unit cell.
- Total contribution from the center atom:
\[ \text{Contribution from center atom} = 1 \]

4. **Calculate Total Number of Atoms**:
- Now, we add the contributions from the corner atoms and the center atom:
\[ \text{Total number of atoms per unit cell} = 1 \text{ (from corners)} + 1 \text{ (from center)} = 2 \]

5. **Conclusion**:
- Therefore, the number of atoms per unit cell in a BCC lattice is **2**.

### Final Answer:
The number of atoms per unit cell in a BCC lattice is **2**.

---