When a cylindircal tube is dipped vertically into a liquid the angle of contact is `80^(@)`. When the tube is dipped with an inclination of `40^(@)` the angle of contact is :

Options

A. `60^(@)`
B. `40^(@)`
C. `30^(@)`
D. `80^(@)`

Answer

To solve the problem, we need to understand the concept of the angle of contact and how it behaves when a cylindrical tube is inclined.

### Step-by-Step Solution:

1. **Understanding the Angle of Contact**:
The angle of contact (or wetting angle) is the angle formed between the tangent to the liquid surface and the solid surface at the point of contact. It is a property of the liquid and the solid material.

2. **Given Information**:
- When the cylindrical tube is dipped vertically into the liquid, the angle of contact is given as \(80^\circ\).
- When the tube is inclined at \(40^\circ\), we need to determine the new angle of contact.

3. **Key Concept**:
The angle of contact is independent of the inclination of the tube. This means that regardless of whether the tube is vertical or inclined, the angle of contact remains the same as long as the same liquid and the same tube material are used.

4. **Conclusion**:
Since the angle of contact does not change with the inclination of the tube, the angle of contact when the tube is inclined at \(40^\circ\) will still be \(80^\circ\).

### Final Answer:
The angle of contact when the tube is inclined at \(40^\circ\) is \(80^\circ\).

---