Question

What should be the order of size of obstacle for diffraction of light?

Short answer

The obstacle size should be on the order of the wavelength of light, approximately 400 to 700 nanometers.

Step-by-step solution

Understanding Diffraction

Diffraction is the bending of light waves around the edges of an obstacle or aperture. This phenomenon is more noticeable when the size of the obstacle or aperture is comparable to the wavelength (\(\text{λ}\)) of the light.

Analyzing Wavelength of Light

The typical wavelength of visible light ranges from about 400 nanometers (\(\text{nm}\)) to 700 nanometers (\(\text{nm}\)).

Comparing Sizes

For significant diffraction effects to occur, the size of the obstacle should be on the order of the wavelength of light. Therefore, the obstacle's size should be comparable to 400 nanometers to 700 nanometers.

Key concepts

Diffraction

Diffraction is a fascinating phenomenon where light waves bend around the edges of an obstacle or through an aperture. This bending causes the waves to spread out and create patterns of light and dark bands. Diffraction is a result of the wave nature of light. When light encounters an obstacle or a slit that is comparable in size to its wavelength, it alters direction and spreads out instead of just passing through or reflecting straight.
Simple examples can help visualize diffraction:

• When you see a pattern of colors around a shadow.
• Light changing direction around a small opening.

By understanding diffraction, we gain insight into many optical phenomena in our everyday lives.

Wavelength

The wavelength of light is the distance between two consecutive peaks of the wave. Visible light has wavelengths that range from about 400 nanometers (nm) to 700 nanometers (nm).

• Violet light has a shorter wavelength, around 400 nm.
• Red light has a longer wavelength, up to 700 nm.

The wavelength of light plays a critical role in diffraction. When the size of an obstacle or aperture is similar to the light's wavelength, significant diffraction effects occur. This is because the waves are able to bend around the edges.
In contexts like telecommunications and microbiology, wavelengths determine how waves interact with different materials and structures.

Obstacle Size

For diffraction to be noticeable, the size of the obstacle or aperture must be comparable to the wavelength of the light being used. In the case of visible light, this means obstacles should be about 400 to 700 nanometers in size. When the obstacle size is either much smaller or much larger than the wavelength, diffraction effects are minimal.

• Objects much larger than the wavelength will cast sharp shadows with minimal bending of light.
• Objects much smaller will cause little to no noticeable diffraction patterns.

Therefore, to observe prominent diffraction patterns with visible light, look for obstacles or apertures that are within the range of 400 to 700 nanometers. This helps in various scientific experiments and technological applications.