Excess pressure can be `(2T//R)` for

Options

A. spherical drop
B. spherical meniscus
C. cylindrical bubble in air
D. spherical bubble in water

Explanation

To determine the conditions under which excess pressure can be expressed as \( \frac{2T}{R} \), we will analyze various scenarios involving drops and bubbles.

### Step-by-Step Solution:

1. **Understanding Excess Pressure**:
Excess pressure is defined as the difference in pressure between the inside and outside of a liquid drop or bubble. It is influenced by the surface tension of the liquid and the radius of curvature of the surface.

2. **Spherical Liquid Drop**:
For a spherical liquid drop, the formula for excess pressure is given by:
\[ \Delta P = \frac{2T}{R} \]
where \( T \) is the surface tension and \( R \) is the radius of the drop. This is because a spherical drop has only one free surface.

3. **Spherical Meniscus**:
Similar to a spherical drop, a spherical meniscus (like that formed in a liquid in a curved container) also has the same excess pressure:
\[ \Delta P = \frac{2T}{R} \]
Again, this is due to the presence of a single free surface.

4. **Cylindrical Bubble in Air**:
For a cylindrical bubble, there are two free surfaces (the inside and outside surfaces of the bubble). The excess pressure is given by:
\[ \Delta P = \frac{T}{R} \]
However, if we consider the total effect of both surfaces, the excess pressure becomes:
\[ \Delta P = \frac{2T}{R} \]
This is because each surface contributes to the overall pressure difference.

5. **Spherical Bubble in Water**:
For a spherical bubble submerged in water, the excess pressure is given by:
\[ \Delta P = \frac{T}{R} \]
This is because the bubble has only one free surface exposed to the water.

### Conclusion:
The excess pressure can be expressed as \( \frac{2T}{R} \) for:
- A spherical liquid drop
- A spherical meniscus
- A cylindrical bubble in air