Tag Archives: light

Solar Energy

What is Solar Energy?

Solar energy refers to the energy from the Sun. It comes to our Earth in form of sunlight and is the widely available form of the energy. It is found at every place, where the Sun is shining. This is the energy that is available everywhere, free of cost, for everyone to use. Another term “solar power” is used, which refers to the generation of power from solar energy. Without solar energy, our Earth would have looked entirely different than it looks today. All the living things on the planet Earth are dependent on the sun.

Solar energy is a type of renewable energy because it will never run out (at least for billions of year). Unlike fossils fuels which are decreasing due to consumption, and are not renewed. Solar energy can be converted into different forms of energy (e.g. mechanical or electrical). People around the world use solar energy for different purposes. In some places, people use solar energy for heating their homes and producing electricity for them. Many countries around the world are using solar energy to generate electricity. Among them, the largest electricity is produced by US and China.

Solar Heating

There are basically two types of solar heating methods. Each one has its own advantages and disadvantages.

  1. Solar passive heating:
    In this method, solar energy is used for heating homes and buildings by using sunlight directly. For example, houses are heated when sunlight enter through the glass windows, heating the materials inside. The heat is then trapped inside the houses and buildings, which also keep them warm during the night. Passive heating is also used in greenhouses to make them warm in the colder areas to grow the vegetables of warm places.
    This method of heating has been used by humans for thousands of years ago for heating houses and drying some fruits and vegetables. The disadvantage of this method is that the things that need to be heated must be placed in the direct sunlight.


    Solar passive heating

  2. Solar active heating:
    Another way to heat houses and building uses solar thermal panels. These panels collect the heat from the sun and warm up the water inside them. Cold water is circulated through these panels and then stored in the tanks as hot water. Then, hot water can be used bathrooms, kitchens, and may be used to heat the house. This method of heating is called active heating because mechanical devices are for collect, distribute and store the solar energy. It provides some advantages over passive heating. The main advantage is that the heat can be collected at one place and utilized at another place. But, extra power is needed to drive the mechanical devices e.g. water pump.


    Solar active heating

Solar Electricity Generation

Another important use of the solar energy is to make electricity from it. Since sunlight is available everywhere, so electricity can be produced at almost every place. All the houses and buildings in remote locations can take advantage from it and may live completely independent from the grid power.


Solar panels installed on a house

There various direct and indirect methods to generate electricity from sunlight. But, mostly used method is the use of solar cells to make electricity from sunlight. Solar cells are also known as photovoltaic cells; these are the semiconductor devices that convert the sunlight directly into electricity. You may have seen these devices in pocket calculators and some handheld device. Solar cells can produce a small amount of power, so they are also connected together in a panel known as a solar panel to increase the amount of power.


Solar Panel

All the houses and buildings that generate electricity from sunlight use solar panels. Solar panels are also common in the satellites because they operate far in space and they provide a source of electricity than can power than for their entire life. Recently in July 2016, a spacecraft has reached the planet Jupiter. This spacecraft generates all of its electricity from solar panels. Moreover, Mars Rovers on the planet Mars also use solar panels to power their motors and science equipment.


Curiosity – Mars Rover

Juno Space Probe

Advantages of Solar power

  • It is the type of renewable energy and will be available for the whole life of our planet.
  • We can use solar panels to generate electricity in remote areas. Whereas, smaller panels can be used to power handheld devices.
  • They produce no pollution to generate electricity, which makes them environment-friendly.
  • They need low maintenance.

Disadvantages of Solar Power

  • Its initial cost is high.
  • It is available during daytime and for the night, backup devices must be used.
  • Backup devices such as lead-acid batteries are quite expensive.
  • During cloudy and rainy days, they are not effective in generating power.


TelescopeThe telescope is an instrument that allows us to see the distant objects closer. We can view objects that are far beyond the range of our eyes. This instrument had opened the new door for us to study the space from the Earth and changed our understanding of the universe. With the help of a telescope, it was proved that the Earth revolves around the Sun and the old geocentric concept was dropped.


First Telescope

Telescope is one of the instruments that was not invented by a scientist. Instead, it was invented by a Dutch eyeglass maker Hans Lippershey. While working with lenses, he brought two lenses in front of each other and found that distant objects were seen closer through them. Then he fitted two lenses (a convex and a concave) in a tube and made the first working telescope. His telescope magnified the distant objects about 3 times. He had applied for the patent but officials said to him that this instrument is too simple to copy, and they didn’t issue the patent.

Galileo Galilei


Galileo Galilei’s Telescope

A great scientist Galileo Galilei when heard about this new invention. He started to build his own telescope, without ever watching the Dutchman’s instrument. He made an improved version of the telescope which magnified the distant object 8 times. With further improvements, he made another telescope with a power of 20. He turned his telescope to the sky and watched the planets, and their moons. He proved that the Earth and all planets in solar system revolve around the Sun. Galileo continued to improve his telescopes and made one with the power of 100, which helped him to study the sky further.

There was a limit in further increasing the magnification of telescope because it decreased the field of view, combined with spherical and chromatic aberration. So, there was need of completely new kind of telescope that can eliminate these problems.

Reflecting Telescope


Newton’s reflecting telescope

Isaac Newton found that the telescopic effect can also be obtained using the mirrors instead of lenses, and he made the first reflecting telescope. These telescopes were called reflecting telescopes or Newtonian telescopes because they used the reflecting power of the mirror to reflect and focus the light. Using mirrors greatly increased the power of telescopes. All the new powerful telescopes were built using the reflecting mirrors and lenses were used in smaller telescopes.

Again the restriction arrived in the further development of the telescope. No matter how much powerful a telescope is, it never gave the clear view of the sky because of the atmosphere. Our atmosphere is filled with a lot of dust and moisture that absorb the light coming from space causing the blurred view of telescopes. For this reason, scientist always dreamed about a telescope that could be brought to space.

Space Telescope

The Breakthrough came in the 20th century when scientists sent the first telescope Known as “Hubble Space Telescope” into space in the year 1990. This telescope orbits 600 km above the Earth. With this new telescope, scientists discovered a lot of new galaxies. They acquired a deep understanding of the universe that was not imagined before it.


Hubble Space Telescope

Light Bulb

Light-BulbToday electric lights have become the important and highly used appliance in our daily lives. We need it for lighting our houses, building and streets etc. Today we have handheld portable lights that can provide a backup time of more 12 hours. The technology that we use today may be different from the past, but what we have today starts back from the invention of the Incandescent light bulb.

Early developments

The efforts to make a working light bulb went back to 1800. When an Italian scientist named “Alessandro Volta” during his experiments on the development of electric battery observed that, when a copper wire between the terminals of the battery is connected, it starts to glow due to the passing of electricity.

The first approach in the development of light bulb was made by Humphry Davy in 1802. When he connected the terminals of the battery to a carbon electrode (used as a filament), it started to glow. This glow didn’t last longer because filament burnt very quickly. His invention is known as “Electric arc lamp”.

Researches and developments on the light bulb were continued by many inventors. Some historians say that the light bulb was invented by 20 inventors before Thomas Edison, but no one was able to make an affordable and durable (long-lasting) design of the light bulb that can be brought into the market.

Thomas Edison – The first practical light bulb


Thomas Edison

The Main problem in the developments of the light bulb was the filament (a conductor that emit light inside a light bulb), it didn’t last too long and melted in a short duration of time. Thomas Edison was very serious in the development of light bulb. He started developing and testing new filaments that could last longer. He tested many materials including carbon, platinum, and other metals. He had developed a carbonized filament that lasted for 14.5 hours. Which proved him, he is going to the right way. He continued developing the filament that can last much longer. He had tried more than 3,000 designs of the light bulb and 6,000 different materials for the filaments. Finally, he found that carbonized bamboo filament can last for more than 1,200 hours continuously. So, Edison used the carbonized bamboo filament in his light bulbs.


Thomas Edison’s Light Bulb

Edison became successful not because he had developed a durable filament, but he developed the whole system of electric lighting including the sockets and buttons for the light bulb. Also, he made world’s first power generating station in 1882.

Other inventors further improved the light bulbs and developed more durable filaments. Later, Edison’s filaments were replaced by these new filaments. Modern incandescent light bulbs use tungsten filaments, due to their high melting point.



Today, cameras have become so popular that, there may be hardly a person who don’t have a camera. We all carry cameras in our smartphones that are always ready to take shots when we want. You are lucky that you are living in a time where we all carry cameras for photography. But Photography, as you know it today was not cheap and common in the past century. Because cameras were not available in shape as we know it today.

The Pinhole Camera

History of the camera goes back to 11th century, a time known as the golden era of Muslims. When a Muslim Arab Ibn Al-Haytham, who was expert in optics invented the camera known as Pinhole camera or camera obscura. This camera was a wooden box, dark from inside with a small hole in it. When light passed through the hole it formed an inverted image inside the box. But, this camera couldn’t preserve the image.


Working of the Pinhole Camera

Image Preserving Camera


Nicephore-Niepce Camera

Camera Obscura was used by artists for tracing the shape of the image, which was formed with light. When the Nicephore Niepce developed a paper that was coated with silver chloride, which when exposed to light, it reacted with light and darkened. He placed this paper inside the camera obscura and the image formed on this light sensitive paper. This was the world’s first photograph that was made using the light in the year 1827. These photographs took about 8 hours to form on the paper and were not permanent, they turned dark when exposed to light.

Permanent Photograph


Daguerreotype Camera

Louis Daguerre partnered with Nicephore Niepce and started working on the way to permanently preserve the image. But, Nicephore Niepce died in 1833 and the further experiments were made Louis Daguerre along with the Niepce’s son.

In the year 1839, Daguerre found an effective process for photography, which he named after himself “Daguerreotype. The images formed with this process were longer lasting and were not affected by light.

Hand-held Cameras


Early Handheld Camera

After the invention of dry plates (a glass plate coated with dried gelatin emulsion), which reduced the time of image formation. The photographers were no longer limited to studios, they used hand-held cameras that were developed at that time to go anywhere to take images. The dry plates were replaced by the flexible roll film made by George Eastman which produced the negatives (photograph used to develop multiple positive photographs) in his camera named the “Kodak”.

Digital Camera

The era of digital cameras was started when the technology needed to make them became available. Fuji DS-1P was a first true digital camera made in the year 1988. It had 2 MB SRAM for storing a digital image until the image was transferred to the computer. But, this model never went commercially. The first commercially available digital camera was DS-X by Fuji, sold at the end of 1988.


Digital Camera

Today, we all use digital cameras in smartphones and we rarely see any old model camera with a roll film except in the technology museums.

What is Electricity?


Electricity is the source of energy that is widely used by the peoples around the world. Today, life can’t be imagined without electricity. We use it all the time for lighting our houses, powering smartphones and computer etc. You have to just push a button and you have the electricity powering your appliances. So, what is the electricity itself? First, we have to understand about the atom and its components to understand the electricity.

An Atom

Atomic-StructureAtoms are smaller particles of matter, so small that millions of them can fit on the tip of a needle. These atoms are not fundamental particles, but they are made up of even smaller particles known as electrons, protons and neutrons. Protons and neutrons are held together in the center (nucleus) of an atom. Whereas, electrons orbit around the center at very high speeds. Electrons carry a negative charge and protons carry a positive charge, but neutrons are neutral (charge less). Both electrons and protons have the same amount of charge. Also, the number of electrons and protons are equal in an atom, which makes the atoms neutral (charge less). Read more about Atom

Since electrons are not bound to one location like protons and neutrons. Instead, they revolve around the center of an atom, so they can be freed from an atom by applying some force. When electrons jump to other atoms throughout the material by some applied force, they create electricity. Therefore you can consider the flow of electrons as electricity, but electricity can also be stored where electron don’t flow. So, Electricity is divided into two types, one is current electricity and other is static electricity.

Current Electricity



Current electricity is the continuous flow of electrons known as “electric current” between atoms in a closed path. The path that is followed by electrons is known as “electric circuit”. The electric circuit needs to be closed for the electric current to flow; e.g. when you push a button to power on a light bulb, you are actually closing the circuit (completing the path for electrons)through which electrons flow to power your light bulb.


Closing the circuit does not mean that electric current will always flow, electric current needs a kind of push known as “electric potential” to go around the circuit. Electric potential is measured in volts, which is supplied by electric utilities to your house at around 120 volts or 220 volts depending on your country.

Static Electricity

Static electricity is the stored form of electricity. It doesn’t flow but can be made to flow in the circuit. Static electricity is made when electrons jump from one substance to other, creating the charge imbalance between them. A substance where electrons jump becomes negatively charged because it has now more electrons than protons, and the substance from where electrons jumped becomes positively charged because it has now fewer electrons than protons. This charge imbalance creates an electrostatic force between the two substances and static electricity is created between them. For example, when you comb your hair, a charge imbalance is created between your hair and the comb. Which creates an electrostatic force between them. That is why your hair are attracted to comb when you bring hair near it.

Static electricity can be converted into current electricity by connecting two substance through a path. Have you ever seen a lightning bolt striking the ground? That was actually static electricity converted into current electricity through the path provided by air.