Molecular forces exist between the molecules of a liquid in a container. The molecules on the surface have unequal force leading to a tension on the surface. If this is not compensated by a force, the equilibrium of the liquid will be a difficult task. This leads to an excess pressure on the surface. The nature of the meniscus can inform us of the direction of the excess pressure. The angle of contact of the liquid decided by the forces between the molecules, air and container can make the angle of contact.
If the excess pressure in a soap bubble is `p`, the excess pressure in an air bubble is

Options

A. `p/2`
B. `p`
C. `2p`
D. `4p`

Explanation

To solve the problem regarding the excess pressure in a soap bubble and an air bubble, we can follow these steps:

### Step 1: Understand the concept of excess pressure
The excess pressure in a soap bubble arises due to the surface tension of the liquid film that forms the bubble. A soap bubble has two surfaces (inner and outer), while an air bubble has only one surface.

### Step 2: Identify the relationship between excess pressures
For a soap bubble, the excess pressure \( P_s \) can be expressed as:
\[ P_s = 2 \times \text{(surface tension)} \times \text{(curvature)} \]
Since a soap bubble has two surfaces, the total excess pressure is twice that of a single surface.

For an air bubble, the excess pressure \( P_a \) is given by:
\[ P_a = \text{(surface tension)} \times \text{(curvature)} \]
Thus, the relationship between the excess pressures of a soap bubble and an air bubble can be expressed as:
\[ P_s = 2 P_a \]

### Step 3: Use the given information
According to the problem, the excess pressure in the soap bubble is given as \( P \). Therefore, we can set up the equation:
\[ P = 2 P_a \]

### Step 4: Solve for the excess pressure in the air bubble
To find the excess pressure in the air bubble, we rearrange the equation:
\[ P_a = \frac{P}{2} \]

### Conclusion
The excess pressure in the air bubble is:
\[ P_a = \frac{P}{2} \]