The surface tension the surface tension of a liquid is 10 N/m. If a film is held on a ring of area 0.01 m square, its surface energy is about Newton

Options

A. `2 * 10^-3` J
B. `2*10^-1` J
C. `2*10^-2` J
D. `2*10^-4 `J

Answer

To solve the problem, we need to calculate the surface energy of a liquid film held on a ring. The surface energy can be calculated using the formula:

\[ E = \gamma \times A \]

where:
- \(E\) is the surface energy,
- \(\gamma\) is the surface tension of the liquid,
- \(A\) is the area of the film.

### Step 1: Identify the given values
- Surface tension (\(\gamma\)) = 10 N/m
- Area of the ring (\(A\)) = 0.01 m²

### Step 2: Calculate the effective area of the film
Since the film is held on both sides of the ring, the effective area will be double the given area:
\[ A_{\text{effective}} = 2 \times A = 2 \times 0.01 \, \text{m}^2 = 0.02 \, \text{m}^2 \]

### Step 3: Substitute the values into the surface energy formula
Now we can substitute the values into the surface energy formula:
\[ E = \gamma \times A_{\text{effective}} = 10 \, \text{N/m} \times 0.02 \, \text{m}^2 \]

### Step 4: Perform the calculation
\[ E = 10 \times 0.02 = 0.2 \, \text{N} \]

### Final Answer
The surface energy of the film is approximately **0.2 N**.

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