Fizeau’s fringes occur in interferometry. One of the most common methods used to test the flatness of a polished surface is by analysing the interference patterns formed when the surface is placed against another polished flat transparent surface. When two surfaces are fully in contact, a pattern of concentric dark and light circles is seen and these patterns (or fringes) …

In volcanoes, lava emerges through a pipe in the top of the mountain. Sometimes, lava also reaches the surface through long cracks in the ground, called fissures. In 1783, lava spilled out of a 32-km (20-mile) long fissure in Iceland and buried 565 square km (218 square miles) of land.

A fern is any one of a group of about 12,000 species of plants. Unlike mosses, they have xylem and phloem (making them vascular plants). They have stems, leaves, and roots like other vascular plants. Ferns do not have either seeds or flowers (they reproduce via spores). By far the largest group of ferns are the leptosporangiate ferns, but ferns …

Eddy currents may be defined as currents induced in a thick conductor when it is placed in a changing electric field. Consider a metallic block placed in a continuously changing magnetic field by keeping the block fixed and changing the magnetic field with the help of an alternating current. Due to the continuous change of magnetic flux linked with the …

Dendrimers are repeatedly branched, roughly spherical large molecules. The name comes from the Greek word “δένδρον” (pronounced dendron), which translates to “tree”. Synonymous terms for dendrimer include arborols and cascade molecules. However, dendrimer is currently the internationally accepted term. A dendrimer is typically symmetric around the core, and often adopts a spherical three-dimensional morphology. The word dendron is also encountered …

Cladistics is the hierarchical classification of species based on evolutionary ancestry. It’s distinct from other taxonomic classification systems because it focuses on evolution rather than similarities between species. This is because it places heavy emphasis on objective and quantitative analysis. Cladistics generates diagrams called cladograms that represent the evolutionary tree of life. The starting point of cladistic analysis is a …

These affect the fingers and toes when they get very cold in winter. An inflammation sets in and produces red swellings that can hurt and/or itch once the coldness wears off.

When the huge plates that cover the Earth move, they create enormous tension that cracks rocks, forming long faults. Blocks of land pushed up between roughly parallel sets of faults form block mountains. Examples include the Ruwenzori Mountain range in Central Africa and the Sierra Nevada in the south-western USA.

People now live and work in high-rise buildings which depend on artificial energy sources like electricity. In the natural world, insects like spiders use a saliva-made fibre to construct their steely web. Termites build intricate airway systems in their habitat. In the same way, some architects and engineers have turned to nature for inspiration when designing buildings. These are called …

Batholiths are enormous masses of igneous rock made up of once-molten material solidified below the earth’s surface. These are usually made of granite and extend over thousands of miles. A well known batholith is located in the Sierra Nevada range of California, across 40,000 sq km.