Volcanoes are mountains whose tops are opened downward. These openings reach below the surface of the earth – where the rock is molten. Volcanoes are mostly closed like a soda bottle, but below which the pressure continues to grow over time. When the pressure reaches a certain level the hot lava suddenly came out. Anybody living near the volcano will certainly become unconscious – after hearing the loud noise.
Formation of Volcanoes
A volcano is built when magma below the surface of earth rises. The rising magma starts to form gas bubbles. These gas bubbles are already dissolved in the magma due to extreme pressures – much like a soda bottle which has carbon dioxide dissolved in it.
Bubbling magma builds-up gas pressure against the surface of the earth under the volcano. When the gas pressure grows to extreme levels – The Volcano erupts – and BOOM! When the eruption occurs, it allows the high pressurized gasses and lava to escape from magma reservoir with earth’s geothermal energy. You can consider this as a way for our earth to release the excess energy.
Magma is the mixture of molten rock, semi-molten rock, and solid particles. It is found below the earth’s surface. When magma is ejected through a volcano – it is called lava. Heat for melting the rock comes from the earth’s geothermal energy.
Lava is the magma after the eruption – having temperatures of 700 C – 1200 C in the liquid state. It doesn’t flow below the earth’s surface – that is the difference between the lava and the magma. Lava is mainly composed of silicon and oxygen. It gets mixed with other elements when it flows from vent towards the ground.
Types of Volcanoes
There are four types of the volcanoes according to the geological and geographical features.
Cinder Cone Volcanoes – These volcanoes are very simple in shape. They are made from the single vent for the eruption of lava. They are very violent and builds-up into a circular cone shape over time. Volcanoes in this type never grow more than a 1000 feet in height.
Composite Volcanoes (Stratovolcano)– These volcanoes are made of many layers of lava. Volcanoes in this type have many layers through which lava can flow. These volcanoes also explode violently and reach a height of 8000 feet.
Shield Volcanoes – These volcanoes cover very large areas, and are very wide. They erupt low-viscosity lava. The slop of these volcanoes is very shallow. As a result, the lava can reach far away. These volcanoes are less violent than other types.
Lava Domes – These volcanoes erupt very high-viscosity lava, which can’t go further away from the vent. As a result, the lava solidifies around the vent and forms a dome that grows over time.
Mauna Loa is the largest volcano found on our Earth – reaching a height of 4 kilometers.
The largest volcano on our solar system is Olympus Mons – its height reaches to 27 kilometers. It is found on the Mars.
Volcanic eruption severely damages the forests around them – sometimes destroys them entirely.
Our Earth has 1500 active volcanoes from which 20 Volcanoes are erupting on the earth at any time.
Is it dark? Just light up a lamp, and you have a source of light to kick-away the darkness. Light is one of the fundamental needs of humans and every living thing (almost!). We can find our ways to home, schools, and offices because of light. Just think a bit, what will happens if the light suddenly goes away? You will be amazed that we cannot survive without light. So, what is that light?
What is Light?
It may be a bit complicated to understand, but let’s try to understand simply. The first thing to remember is that light isn’t made of matter, so it doesn’t have mass. It is just a form of energy (also called electromagnetic energy) that travels at a constant speed from one place to another and reflects from the objects. When it hits our eye, we see the objects from which the light is reflected or emitted.
So, do we really see light? The simple answer is NO!
We only see the effect of light that happens in our eyes. The light cause a chemical reaction in light-sensitive cells of our eyes. These reactions produce electrical signals that are transferred to the brain by the optic nerve.
Moreover, light is the small portion of the electromagnetic spectrum that our eye can detect. The other portions of electromagnetic radiation that you may be familiar are radio waves, infrared, ultraviolet, and X-rays etc. But, the human eye cannot detect these radiations. Our eyes are only sensitive to light, also called visible light.
Here is the complete electromagnetic spectrum
Notice, how much small portion is occupied by visible light spectrum.
How Fast Light Travel?
Visible light and every radiation of electromagnetic spectrum travel at constant speed, which is 299,792,458 m/s (meter per second) or 186,000 miles/second. It only takes 1.3 seconds for the light to reach from the moon to earth, and 8 minutes to reach from the sun.
The speed of light is the fastest known speed in our universe, and no object with mass can reach that speed. Although, material objects can reach close to the speed of light.
The interesting part!
The laws of classical physics don’t work anymore when objects reach near the speed of light. Then, comes Einstein’s theory of relativity to rescue us. This theory describes what happens when things reach closer to the speed of light.
How Do We See Colors?
The visible light not only allows us to see objects, but it also allows us to see the object in a wide variety of colors. It is because the visible light starts from the wavelength of 700nm and ends at 400nm. The colors that we can see a change from 700nm (dark red color) to 400nm (dark blue color).
Here is the complete spectrum of visible light.
The colors we see may be the single wavelengths of light or the mixture of several wavelengths. For example, the sunlight is the mixture of all wavelengths of light and we see it as white light. Just check the light spectrum image above and notice that there is no white color, it just a mixture of colors.
As you know from the above discussion that, white light is the mixture of colors. So, when this white light falls on an object, it absorbs some colors of light and reflects the remaining colors to the surrounding. When our eyes catch that reflected light, it sees the object’s color that it reflected.
For example, when the light hits the green box, it absorbs all the colors of light and reflects only green color. As a result, we see it as green. Similarly, black colored objects absorb all the colors of light so we see it as black. Furthermore, the white colored objects don’t absorb any color at all, so we see them as white.
There are some materials which don’t absorb light or reflect them. As a result, we can see through these objects. These objects are called transparent objects, e.g. glass.
How Light Helps Us
The first benefit that will come to everyone’s mind is that light helps us and every organism on earth to see objects and the environment. Besides that, there many other important benefits of light, which are:
The heat from the sun reaches the earth as radiation. These radiations are absorbed by atmosphere and ground to maintain the temperature of our earth that is suitable for life. Without that heat, everything would be frozen like the planet, Pluto.
Plants use sunlight in Photosynthesis to prepare food for them and generate oxygen for us.
We use solar panels to generate electricity from light.
We are using spectroscopic analysis of electromagnetic radiation coming from space to study the far planets, stars, and galaxies.
The speed of light reduces as it enters into a medium, like air, glass, and diamond.
Ants can see the ultraviolet region of light, which humans can’t see.
Ibn al-Haytham was a Muslim scientist, who first discovered that we see objects due to the light coming into our eyes. Before him, it was considered that we see because eyes emit radiations that hit surrounding objects. Ibn al-Haytham is also considered as the father of Optics (Science of light).
Have you ever tried to jump?
Probably, yes! And you know that when we jump from the ground, we just fall back after few seconds.
Why? And How?
These are the questions that, almost every human had thought in his childhood. So, the simple answer to all these questions is “gravity”.
So, let’s learn something about gravity and the interesting history about it.
What is Gravity?
Gravity is the force that attracts us and other objects towards each other; much like a magnet, but not as a magnet. Then, why things in your room are not attracted to each other? It is because gravity depends on the mass; Massive objects have more gravity.
Gravitational force is so weak that the object must be very massive to have sufficiently strong gravity to attract other objects. Consider our earth, it so massive that its gravity pulls us towards the ground. When we jump, earth’s gravity pulls us and we fall back on the ground.
Importance of Gravity
What would happen, if gravity suddenly disappears? Take some time and think about it.
You will be amazed to find out that, the current appearance of our earth, planets, and stars depends on the gravity. Without gravity, there will be no earth’s pull to attract you back to the ground when jumping. Even the planets and stars would not exist without gravity. Because planets and stars have been formed from the accumulation of cosmic dust and gas that was only possible due to gravity.
Here are some of the effects of gravity on our everyday life
We can stand, jump, walk, and run on the ground due to gravity. If the earth doesn’t pull you back while jumping, then you would never come back to the ground, and you may reach space in a single jump! Wow!
On the earth, gravity keeps the air around us as a blanket, and it prevents air from escaping into space.
Tides in the oceans are caused by the gravitational pull of moon and sun.
Universal Law of Gravitation
Don’t be afraid!
It is just a simple law that was proposed by a famous scientist Sir Isaac Newton. This law gives us the relation between the gravitational force, the mass of objects, and the distance between objects.
Here are two simple points that explain the law:
The gravitational force between massive objects is more as compared to light objects.
The gravitational force between two objects decreases exponentially as they go away from themselves.
Here is the mathematical expression of the universal law of gravitation:
F = G*M1*M2/r^2
G = Gravitational constant, whose value is equal to M1 = mass of the first object M2 = mass of the second object r = distance between two objects
By knowing gravity, you can calculate when a ball will touch the ground after being released into the air. You can measure and graph the path of a projectile. You can calculate how much propellant is required to push a rocket into space, and many more.
Do Heavy and Light Objects Fall at the Same Time?
The simple answer is, yes. But let’s understand, why it happens.
Gravity at the surface of the earth is 9.8 m/s, which means an object falling towards earth gains 9.8 m/s speed in every second. If a ball is dropped from a building it will have 9.8 m/s speed at the end of the 1st second, 19.6 m/s at end of the 2nd second, and 29.4 at the end of the 3rd second and so on. Every object is accelerated at the same rate towards earth, whether it is a paper clip or a stone. If two objects are dropped from a height, they both will hit the ground at the same time.
But, wait a minute!
You may be thinking, why a paper falls slower than a paper clip when both are dropped from the same height? It is because of the air resistance. The paper clip has lower surface area than the paper, which results in higher air resistance for the paper. But, if you drop paper and paper clip into a vacuum chamber both will hit the bottom at the same time. It is because vacuum chamber does not have air, so there will be no air friction to slow any object.
Difference between Mass and Weight
In everyday life, you may have used the term mass and weight interchangeably. But in physics, mass and weight are two different quantities.
The mass of an object is the quantity of matter in it; usually measured in kilograms. But, weight is the force of an object that it is putting on a platform due to gravity.
For example, if you hold a brick in your hand you will feel a downward force. If you somehow take that brick to the moon, you will notice much less downward force. Because the moon has less gravitation than the earth. In both cases, the amount of the matter in the brick will be same on the earth and the moon.
Difference between Gravity and Gravitation
There is a difference between gravity and gravitation. Gravitation is the force of attraction between objects that have mass. But, gravity is the gravitational force between earth and other objects. It means that gravity is the special case of gravitation.
Gravitational force exists since the formation of our universe. It is one of the four fundamental forces of nature. It is the force that attracts atoms together to form stars and planets. It keeps the moon in orbit around the earth and the earth around the sun.
Gravity keeps all the planets in the orbit of the sun, and it keeps our moon in orbit of the earth.
If any object goes upward with a velocity of 11 km/s, it will escape the gravitational pull of the earth. This velocity is called the escape velocity, and it is different for different planets and moon.
The gravity of our sun is about 274 m/s^2. Anything weighing 1 kg on the earth will weigh about 28 kg (If it was possible!).
A Brief History
Let’s learn something about the history of gravity, and find out about the people who contributed to explaining the gravity.
Who first pointed to the presence of gravity? And when? It is still unknown. But you may consider that early human beings had probably thought about it. Because, it is the force whose effects we can clearly see, like falling back to the ground after jumping.
The first person who gave the hypothesis about gravity was, Aristotle. He hypothesized that “heavier objects are accelerated more towards ground than lighter objects”. He was actually wrong because he didn’t know about air resistance which slows down the objects. But, he at least provided the ground for the great scientists to think and research about gravity.
In late 16th century, a famous scientist Galileo Galilei performed an experiment. In this experiment, he dropped two balls from a height and proved that light objects and heavy objects fall at the same rate.
In 1687, Sir Isaac Newton developed the universal law of gravitation. Which explained that lighter objects have less gravitational force of attraction than massive objects. Also, the gravitational force decreases exponentially as the distance between two objects increase. This is also known as the inverse square law.
The modern understanding of gravity was described by Albert Einstein. He described the gravity as a curvature in space and time. This curvature is caused by the objects with mass; the massive objects cause more curvature than the lighter objects.
You may have probably played with magnets in your childhood. These magnets attract and repel each other. Kids love to stick magnets on iron objects and on their fridge. But, magnets are more than just a toy for playing. Today, magnets play important role in shaping our modern world. Everybody is somehow dependent on it. Let’s find out the amazing information and their facts.
What is Magnetism?
Magnetism is a physical phenomenon that arises due to the motion of the charged particles, like electrons in the magnets. The moving electrons produce a field around them that is called magnetic field. This magnetic field is the cause of the magnetic effects that you observe when playing with magnets, like attraction and repulsion. The magnets that you have played with are called permanent magnetic. These magnets mostly contain iron metal. The iron and few other metals that can become a magnet, or attracted towards them are called ferromagnetic materials (we will discuss them in later sections).
You may be thinking, how and why electrons move in the iron?
The simple answer is that the electrons continuously revolve around the nucleus of atoms. Moreover, electrons also jump from atoms to atoms, which further contribute to the overall motion of the electrons that produce magnet field. Now you may be thinking that iron metal has a motion of electron that produces a magnetic field. Then, why every iron material does not have magnetism? To answer this, let’s understand the concept of magnetic domain.
Each atom in the iron (and other ferromagnetic materials) material produce a very small magnetic field due to the motion of electrons. These individual magnetic fields point to a direction according to the orientation of their respective atoms. The orientation of these atoms is random. So, it forms regions in the iron object (and other magnetic materials), in which the overall magnetic field of the atoms points to the same direction. These regions are called magnetic domain.
You can simply consider each magnetic domain as a region, in which all atoms produce the magnetic field in the same direction. In non-magnetic iron objects, these domains are randomly aligned. As a result, the total magnetic field of that iron object is zero, and it behaves as a non-magnetic object. When all the magnetic domains are aligned in the same direction, then their magnetic fields are added and results into a magnet.
There are many techniques which are used to make an ordinary iron object into a permanent magnet. The simple to do this is to rub a magnet on an iron object in one direction for 20 times. This will reorient the magnetic domains to point their magnetic fields in the same direction. As a result, the ordinary iron object will become a magnet. You also make the screwdrivers in your home into a magnet. This will make it easier for you to pick screws.
How the Magnets Attract or Repel?
Recall your memory that, magnets have two poles. One is called North pole, whereas other is called South pole. When you bring the south pole of one magnet near to the south pole of another magnet, they will repel each other. Same is the case when you bring north poles together. But, when you bring the north pole of one magnet near to the south pole of another magnet, they will attract each other. The attraction and repulsion effects, both are simple as well as complicated to understand. But here, we will try to understand them in a simple way.
The magnetic field of a magnetic has a direction, which points from the North Pole towards the South Pole. For simplicity, you can consider that the magnetic field starts from the North Pole and ends at the South Pole. Let’s understand magnetic attraction and repulsion separately.
The magnetic field that is started from the North pole must terminate at the South pole. So, when you bring the North Pole of one magnet near to the south pole of another magnet, they will attract each other. Because, magnets always try to reduce the gap between their opposite poles, so that magnetic field can complete its path quickly.
The repulsion occurs when the same poles (North-North, or South-South) are brought together. It is because the same poles are not completing the path of the magnetic field, but disturbs its path. So, magnets try to repel each other until they are far from each other.
You may have probably observed that magnets can stick on iron materials. But, there are also other materials on which magnets don’t stick, like clothes, plastics, and glass. This is because all the materials that we know are categorized into 3 categories. The categories are made according to the way the materials behave with magnets or magnetism.
Here is the quick intro of these material categories:
These materials are strongly attracted towards the magnets. It is because their atomic structure allows them to easily pass the magnetic field through them. Some of the ferromagnetic materials are iron, cobalt, and nickel.
These materials feel very small attraction from You won’t even notice this attraction. Some of the examples of this category are Aluminum, zinc, and sodium.
These materials are not attracted to the magnets. Instead, they try to avoid them. If you bring a very strong magnet near a lightweight diamagnetic material, you will notice a slight repulsion. Some of the examples of diamagnetic materials are water, copper, and gold.
What is an Electromagnet?
Up to here, it was all about the permanent magnets, which remain magnets after the magnetization. There is also another type of magnets, called electromagnets. Electromagnets are similar to permanent magnets; they attract and repel each other and stick to iron objects. The difference is that they only become a magnet when the electric current passes through them. The larger the current flow, the stronger the magnet will become.
The electromagnets are usually made by wrapping the enamel coated wire around a ferromagnetic material like iron. When current will flow through the wire, the magnetic field will be produced. One thing to remember is that if the wire is wounded on a ferromagnetic material for making an electromagnet. Then after the current is blocked, the iron object will become a weaker permanent magnet than the electromagnet itself. So, if there is a need of temporary magnetism, iron is not used as a core in electromagnets.
Magnets are the essential part of our modern life. Without magnets, you can’t imagine how our world will look like. It is used from our common household items and gadgets to big industries. Here are few uses of magnets:
Electric Motors: The electric motor in the toys, water pumps, and fans in a house use magnetism. They use magnetism to convert the electrical energy into rotation. Larger industries also use motors in their processes.
Computer Hard Disk: Today, computer hard drives can store several TBs (1 TB = 1000 GBs) of data. All this data is stored in the plates which are magnetized.
Loud Speakers: Loudspeakers have small electromagnets that vibrate according to the electric signal it receives from a phone, a computer, or a TV to produce sound.
Weight Lifters: Many weightlifters, lift the weight which contains These lifers have very strong electromagnets to lift heavy iron objects like cars and containers. The electromagnets are only turned ON when the weight needs to be lifted and carried.
MRI Scanning: Magnetic Resonance Imaging is the technique which is mostly used by physicians. MRI is used to make the images of the organs, bones, and other internal body structures by using strong electromagnets.
A Brief History of Magnets
Let’s dig a little bit into the history of magnets and find out its discovery and progress over time?
Magnets were known to mankind since ancient times. Both Greeks and Chinese claim that the magnet was discovered by them. The first discovered magnet was a stone made of iron ore. It was called lodestone. Ancient people believed that the lodestone has magical powers. These powers allow it to attract iron objects. They thought that lodestone can be used to cure the sick and provides protection against evil spirits.
Later on, people realized that when lodestone is shaped into a needle and placed on a leaf floating on the water, always points in the same direction. This led them to the invention of the compass and due to this reason lodestone was sometimes called “leading stone”.
In the 1600s, William Gilbert experimented on magnets and found out that our Earth is a giant magnet (a brilliant discovery). He also found that by rubbing a magnet on an iron object in the same direction makes it a permanent magnet. Moreover, he also told that by heating the permanent magnet, its magnetism is lost.
A very clever discovery in the field of magnetism was made by Oersted in 1820. He discovered the relation between electricity and magnetism. He found that, when current passes through a coil, it deflects the compass needle. Thus, he concluded that electric current produces a magnetic field. Today our electric motors work on his discovery.
In 1831, Michael Faraday discovered that by moving a magnet through a coil, it produces the electric current in the coil. This principle is known as “Faraday’s Law of Electromagnetic Induction”. The electric generators work on that principle, and again this law further revolutionized the world. Today, our electricity is produced on the basis of this law at power stations.
Earth is a giant magnet. It produces its magnetic field due to the flow of liquid iron at about 6,000 C (10,800 F) flowing in the center of the Earth.
It was once believed that there are islands on earth, made entirely of magnets. They attracted the ships near them, due to iron nails. Resulting in the destruction of the ships.
Many birds and sea creatures sense the Earth’s magnetic field like a compass to guide their way.
The magnetic field of the Earth protects us from the deadly solar winds.
Plants are an important part of nature. They are everywhere in the world and makes our planet green. We all know that they are good for us because they provide us food, wood, and the precious oxygen. But, there are many species of plants that also carry poisons. These poisons may cause itching, vomiting, diarrhea, and even death. The poisonous plants play an important role in nature. Let’s dig in deep!
Why Plants Carry Poison?
The first question that everyone will probably ask about the poisonous plants is that, why plants carry poison with them? Because we know plants as good creatures that provide a primary food source to animals, so why they will want to harm the animals? There are some reasons behind it, let’s discuss them.
The primary reason to carry the poison is the protection from herbivores. Herbivores (plant eaters) consume the plants to survive. Suppose if some herbivores start to eat one plant together, they may consume the whole plants. As a result, the plant will die completely. So, some plants have evolved to carry poison in them with varying amount of poison to protect them against herbivory when they are consumed more than average.
Some plants carry permanent poison to protect themselves from herbivores. For examples, leaves of mangrove tree are poisonous to many herbivores. But, few herbivores are able to digest these poisonous leaves, e.g. sloths. As a result, few species can eat these leaves which helps mangrove to survive while providing food to limited herbivores.
Uses of Poisonous Plants
Poisons of the plants are of course harmful to animals and humans. But, they are also used by humans in the preparation of some medicines and in some other applications. For example, people have used the poison of ‘Buckeye’ for catching fishes. ‘Digitalis’ plant has provided the first remedy for cardiac, which helped in strengthening the heartbeat.
The Most Poisonous Plants on Earth
Here are some of the plants that are considered most poisonous in the world.
1. Aconitum napellus
It is a beautiful plant with purple color. When eaten it may cause numbness, vomiting and also death. In 2014, BBC reported that a 33 years old gardener died due to touching (or eating) this plant.
2. Castor Bean
When this plant is eaten, it may cause vomiting, bloody diarrhea, increased heart rate, low blood pressure, and death in few days (if the victim is not treated well).
3. Water Hemlock
It is also a beautiful plant with small white-colored flowers. This plant may cause seizures if eaten. It is also the common poisonous plant in UK and US.
Leaves of the apple tree and its seeds contain ‘cyanide’; a very poisonous chemical.
Unripen potatoes are also poisonous. They may cause vomiting.
Some poisonous plants can cause very intense itching when touched, e.g. Poison Ivy.