Photovoltaics: an alternative 'Sun' for solar cells

A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...

Spontaneous Chemical Reactions
Spontaneous redox reactions occur abundantly in nature. The chemical reaction occurring in a disposable AA battery powering our remote controls is one such example of a spontaneous redox reaction. Another example is the immersion of coiled copper wire into an aqueous silver nitrate solution. The reaction shows a gradual, visually impressive color change from colorless to bright blue and the formation of a grey precipitate on the copper wire. In this experiment,...

A battery is a galvanic cell that is used as a source of electrical power for specific applications. Modern batteries exist in a multitude of forms to accommodate various applications, from tiny button batteries such as those that power wristwatches to the very large batteries used to supply backup energy to municipal power grids. Some batteries are designed for single-use applications and cannot be recharged (primary cells), while others are based on conveniently reversible cell reactions that...

A device consisting of two electrical conductors that are separated by a distance and used to store electrical charges is called a capacitor. The space between the conductors is either a vacuum or an insulating material, called a dielectric. Capacitors have many applications, ranging from filtering static from radio reception to energy storage in heart defibrillators.
When the conductors are two identical parallel plates, it is called a parallel plate capacitor. When battery terminals are...

Photosynthesis is a multipart, biochemical process that occurs in plants as well as in some bacteria. It captures carbon dioxide and solar energy to produce glucose. Glucose stores chemical energy in the form of carbohydrates. The overall biochemical formula of photosynthesis is 6 CO2 + 6 H2O + Light energy → C6H12O6 + 6 O2. Photosynthesis releases oxygen into the atmosphere and is largely responsible for maintaining the Earth’s atmospheric oxygen content.

All living organisms on Earth are directly or indirectly dependent on photosynthesis. It is the only biological process that can capture energy from sunlight and convert it into chemical energy that every organism can use to power its metabolism. Photosynthesis is also the source of oxygen required by many living organisms.
Types of Organisms Based on their Modes of Nutrition
Broadly, there are two main categories of organisms based on their modes of nutrition — autotrophs and...