First stated by Camille Jordan in 1887, the Jordan Curve Theorem says that any simple closed curve in a plane divides the plane into two disjoint regions (inside and outside of the curve). By simple closed curve, roughly a curve which does not cross itself but eventually joins itself; more formally, the theorem refers to any homeomorphic image of a …

Histogram is a very useful tool in photography, found on all the digital cameras (compact cameras and DSLR cameras), as well as in all the photography editing programs. With the histogram you can analyse the tonal value of the image or in other words: it shows how bright or dark the image is (number of tones captured at each brightness …

The hermit crab is a type of crab that doesn’t have a very hard shell. Since its shell is not strong enough, it uses old shells of other animals for protection, especially that of old whelk. This habit of living in a second-hand shell gives rise to the popular name ‘hermit’ crab. Most hermit crab species live on the ocean …

A heat budget is the perfect balance between incoming heat absorbed by earth and outgoing heat escaping it in the form of radiation. If the balance is disturbed, then earth would get progressively warmer or cooler with each passing year.

A gyroscope is any rotating body that exhibits two properties: gyroscopic inertia or rigidity in space and precession or the tilting of the axis at right angles to any force tending to alter the plane of rotation. These properties are inherent in all rotating bodies, including the Earth. The term gyroscope is applied to spherical, wheel-shaped or disk-shaped bodies universally …

A straight line drawn between two places on a world map looks like the shortest distance between them. But this usually isn’t so, because most maps are distorted. Take a look at a globe. If you stretch a piece of string over the globe, joining Japan and Denmark, you will see that the shortest route runs over the North Pole, …

Gluten is a protein found in wheat, rye and barley. In some genetically predisposed children, food containing gluten causes small-bowl mucusal damage resulting in a disease called gluten-sensitive enteropathy or celiac disease. The treatment is a strict gluten-free diet i.e. elimination of wheat, rye and barley products from the diet. Gluten-free foods are commercially available.

A flipbook is a small book with a series of printed images that create the illusion of motion when its pages are rapidly flipped. Typically, a flipbook is held in one hand while the thumb of the other flicks the pages and the user concentrates on the middle of each page. The flipbook relies on a basic optical principle known …

It is a type of wide-angle lens used in photography to capture extremely wide and hemispherical images. Its focus length varies between 8-10 mm for circular lenses and 15-16 mm for full frame lens. Originally developed for use in meteorology and astronomy, it is used in planetariums and dome theatres to show pictures on a broad canvas.

In Rail Terminology: A fishplate, splice bar or joint bar is a metal bar that is bolted to the ends of two rails to join them together in a track. The name is derived from fish, a wooden bar with a curved profile used to strengthen a ship’s mast. The top and bottom edges are tapered inwards so the device …