In order to see diffraction the thickness of the film is

Options

A. 100 A
B. 10,000 A
C. 1mm
D. 1cm

Answer

To determine the thickness of the film required to observe diffraction, we need to consider the relationship between the thickness of the film and the wavelength of the light that is incident on it. Here is a step-by-step solution:

### Step-by-Step Solution

1. **Understanding Diffraction**:
- Diffraction is the bending of light waves around the edges of an obstacle or aperture. It is most noticeable when the size of the obstacle or aperture is comparable to the wavelength of the light.

**Hint**: Remember that diffraction occurs when the dimensions involved are on the order of the wavelength of light.

2. **Wavelength of Light**:
- The wavelength of visible light typically ranges from about 400 nm (nanometers) to 700 nm. In angstroms, this translates to approximately 4000 Å (angstroms) to 7000 Å.

**Hint**: Convert the wavelength of light from nanometers to angstroms for easier comparison with film thickness.

3. **Thickness of the Film**:
- For diffraction to be observable, the thickness of the film must be comparable to the wavelength of the light. This means that the thickness should be on the order of the wavelength of the light used.

**Hint**: Think about the relationship between the thickness of the film and the wavelength of the light; they should be of the same order.

4. **Conclusion**:
- Since the wavelength of visible light is in the range of 4000 Å to 7000 Å, the thickness of the film should also be around this range. For practical purposes, we can say that the thickness of the film should be on the order of 10,000 Å to ensure that diffraction effects are noticeable.

**Hint**: The thickness of the film should be at least in the range of the visible light wavelengths to observe diffraction clearly.

### Final Answer:
The thickness of the film required to see diffraction is approximately **10,000 Å** (angstroms).