Category Science

What is Digital Electronics?

DIGITAL ELECTRONICS

In many electronic circuits, such as those in radios, the current can be of any strength. These circuits are called analogue circuits. In digital circuits, the current can have only two strengths – on and off. Digital circuits are used in devices in which the flow of electricity represents information, such as computers.

Numbers are represented in digital circuits using the binary number system. This uses only the digits 0 and 1 and so can easily be represented in electronic circuits by turning currents on or off. In the decimal system (numbers we use in everyday life: 1, 2, 3, etc.), the digits of a number represent ones, tens, hundreds and so on. In the binary system, the digits represent ones, twos, fours, eights and so on. In digital circuits, each 0 or 1 is called a bit. A four-bit binary “word” can represent decimal numbers up to 15 (one 8, one 4, one 2 and one 1).

Almost any sort of information (from simple letters to complex moving images) can be represented by numbers, which in turn can be represented in binary form. This means that any sort of information can be represented in digital electronic circuits. Computers rely on this fact to store numbers, words, pictures and sounds. They use circuits called logic circuits to process and manipulate the information.

Many types of analogue information must to be turned into digital form before they can be handled by digital circuits. This process is called digitization. For example, in a microphone, a sound, which is created by waves of air pressure, is turned into a changing electric current, called an analogue signal that represents the changes in pressure. This is turned into a digital signal by an electronic circuit called an analogue-to-digital converter. It repeatedly measures the analogue signal, turning it into a continuous stream of binary numbers.

In telephone systems, the sound of your voice is digitized, normally at the telephone exchange, before it travels across the telephone network. Before it arrives at the telephone of the person you are talking to, it is turned back to an analogue signal (which is needed to work the speaker) by a digital-to-analogue converter. The same thing happens in a CD player, because sound is recorded in digital form on a CD.

The pixel code is stored as a binary number, which, inside the computer, exists as electrical signals. 1 means an electrical pulse, 0 means no electrical pulse.

DIGITAL PICTURES

Anything that appears on a computer’s monitor is called computer graphics. These can be as simple as plain white text on a black screen, or as complicated as animated three-dimensional images. Whatever the graphics are, they are made up of small coloured squares called pixels (short for picture elements) in a grid pattern.

The concentration of pixels in a picture is called resolution. High-resolution graphics can be viewed on a large screen without the pixels being visible. Graphics can have a different range of colours, too. In eight-bit graphics, each pixel is represented by eight bits, and so can be any one of 256 colours.

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What are Integrated Circuits?

INTEGRATED CIRCUITS

Single electronic components are normally soldered (connected by metal) on to a circuit board by their legs. Metal tracks on the board connect the components together. Circuits that require hundreds or thousands of components would be enormous. Modern circuits use integrated circuits, or microchips, in which microscopically small components and the connections between them are built into a wafer of semiconductor material, which is normally silicon. This is why integrated circuits are often called silicon chips. There are thousands of different integrated circuits. Some, such as amplifier chips or timing chips, contain a few dozen components. Others, such as computer processors or memory chips, contain hundreds of thousands or even millions.

The first integrated circuit was built in 1959 in the USA by Texas Instruments. Since then the number of components that can be fitted on to a chip has increased rapidly. An integrated circuit starts life as thin wafer of semiconductor material. The components are built into it by adding and removing layers of semiconductor material, conductors and insulators, using complex chemical and photographic processes.

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What do you understand about Electronics?

ELECTRONICS

Electrons are tiny particles that are parts of atoms. An electric current is a flow of electrons. Electronics is the study of how electrons behave and how they can be controlled so that they can do useful jobs. Nearly all the machines we use in our everyday lives – from radios, calculators and television remote controls to telephones, computers and cars – contain electronic circuits that make them work. Electronics are especially important in information technology and communications.

The study of electronics began at the end of the nineteenth century, and had its first practical use in the early 20th century in the development of radio communications. The first electronic devices were called thermionic valves. These included the diode valve, which allowed current to flow through it one way but not the other, and the triode, in which a small current could be used to control a much larger current. The parts of thermionic valves, some of which glowed red hot, had to be enclosed in a glass tube with the air removed to create a vacuum.

In the 1950s valves were quickly replaced by semiconductor devices. A semiconductor is a material that can act as both a good conductor of electricity and an insulator. Semiconductor devices are much simpler, smaller and more reliable than valves.

A thermionic triode valve was designed to amplify (strengthen) electric signals. A central electrode is heated inside a glass tube. Electrons flow from it to another, outer electrode. A small electric signal causes large changes to this electron flow, producing a more powerful electric signal.

There are dozens of different electronic components, but the most common ones are resistors, capacitors, diodes and transistors. A resistor restricts the flow of current in a circuit. Capacitors store electric charge. Current can flow into them until they are full, and out of them until they are empty. A diode allows current to flow one way but not the other. A transistor can act as a switch or an amplifier. It has three connections. The current flowing between two connections is controlled by a tiny current flowing into the third.

An electronic circuit is made up of components linked together by wires around which an electric current flows. By combining different components and connecting them in different ways, it is possible to make electronic circuits which do almost any job. In an electronic circuit, the components of the circuit itself control the current. For example, in a security light, the electric current is turned on or off by an electronic device that detects whether it is dark and whether anybody is moving nearby.

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How wood frogs freeze?

Wood frogs inhabit parts of the U.S., Canada and the Arctic Circle which means, they must be prepared to deal with sub-zero temperatures. While different animals do different things – such as burrowing underground and migrating to warmer places – to escape the cold, creatures such as wood frogs embrace it – they simple freeze! Let’s see how they do it.

They become frogcicles!

When winter arrives and the first ice crystals fall on this freeze-tolerant frog’s skin, the frog begins to freeze. As this happens, the liver starts to produce large quantities of glucose. Once this glucose is released from the liver, it mixes with the bloodstream and is carried throughout the body through the pumping of the heart. Research says urea – produced by the frog’s urine – also blends with the glucose. This mixture helps prevent the cells from freezing completely, because that would mean the death of the frog. Only about 70% of its body fluid freezes. Meanwhile, the frog stops breathing, its heart too stops beating, and organs become inactive. The frog hardens – this is offhandedly referred to as a frogcicle, drawing from the word icicle. The creature is motionless and appears dead. This continues through the winter. While the role of glucose in keeping it alive when it is frozen has been understood, it is still not clear what causes the stopping of a beating heart. As for the frog, when Spring arrives, it begins to thaw, regains consciousness and recovers from its state within a day. And, life goes on – with a freeze-thaw cycle in place.

 

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COVID and new kind of pollution

The COVID-19 pandemic is far from over. While healthcare workers, governments and people continue to fight the coronavirus, a new environmental problem has emerged and has been crying for attention – pandemic-related pollution, especially those concerning medical and plastic waste. The increased use of masks, gloves and PPE (Personal protective equipment) during the pandemic has resulted in them making their way into oceans and landfills. According to the UN Environment Programme (UNEP), around 75% of the used masks and other waste will end up in landfills, or seas. One study estimates that in the U.K. alone, if every person used a single-use face mask a day for a year, it would create an additional 66,000 tonnes of contaminated waste.

Plastic everywhere

The PPE includes respirators, masks, face shields, goggles, gowns, coveralls, and more. These are made of plastic and are mostly used only once before disposal. Such items take up to 500 years to degrade in the ocean. Similarly, gloves, commonly made from cheap and durable plastic such as polyvinyl chloride, take longer to degrade.

Cause for concern

The UNEP has warned the governments about the potential consequences of such waste. Open dumping of used masks, PPE and gloves, and their burning can not only lead to the release of toxins in the environment, but also to secondary transmission of diseases.

Environmentalists are urging governments to treat the medical and hazardous waste effectively. They insist on educating the public on the safe disposal of waste.

Innovation is key

Meanwhile, many plastic-free or reusable alternatives are being suggested worldwide to tackle the issue. A decontamination system that could instantly treat large quantities of PPE, masks and respirators, use of UV light to decontaminate used items and biodegradable gloves and face visors are being mooted.

 

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What are the phases of the Moon?

Every night many of us eagerly wait for the Moon to rise. But each night, the Moon looks slightly different from what it did the previous night. Sometimes the Moon looks like a narrow crescent, while at other times it looks like a big circle. On some nights, you might not see the Moon at all. These different shapes of the Moon that we see at different times of the month are called the Moon’s phases.

Does the Moon really change shapes?

No, the Moon does not change its shape. But it appears different to us because our view of the Moon changes based on how much of the Moon is illuminated by the Sun. The Moon does not produce its own light. It depends entirely on the Sun for light, like all the planets in our solar system. The Sun’s light comes from one direction, thereby illuminating one half of the Moon that is facing the sun, while the other half remains in darkness.

On Earth, our view of the illuminated part of the Moon changes each night depending on where the Moon in its orbit around the Earth. When we see the completely illuminated part of the Moon, that phase of the Moon is known as a Full Moon.

Each night following the Full Moon, as the Moon orbits around the Earth, we start to see less of the Moon illuminated by the Sun until we see no Moon at all. This phase is called the New Moon, when the far side of the Moon is facing the Sun and the side facing the Earth is dark.

The eight phases

According to NASA, the Moon has eight phases which we see one after the other as the Moon completes its cycle around the Earth. It takes the Moon 27 days to orbit Earth. The eight phases are:

New – When we cannot see the Moon at all

Waxing Crescent – When we see the Moon as a think crescent opening to the left. Waxing is when the Moon is growing with light.

First Quarter – When we see the first quarter phase of the Moon which appears to us as a Half Moon.

Waxing Gibbous – The phase between Half and Full Moon, when most part of the Moon can be seen.

Full – When we see the Moon completely illuminated.

Waning Gibbous – The phase between Half and Full Moon. Now, the view of the Moon is getting smaller.

Third Quarter – The third quarter of the Moon, seen as Half Moon on Earth. In this, the opposite half of the First Quarter is illuminated and visible.

Waning Crescent – When we see the Moon as a thin crescent opening to the right.

 

Picture Credit : Google