Lightning
Lightning is a natural phenomenon in which an electric discharge occurs in nature on a massive scale. It happens because of the accumulation of charges in the cloud due to fictional or static charging.
It can be destructive and can damage life and property.
Benjamin Franklin was the first one to prove that lightning and static discharge both have the same nature of origin, i.e. fictional or static electricity.
What are electric Charges?
Every material is made up of atoms which are again made up of three elementary particles known as an electron(negative charge), proton(positive charge) and neutrons.
In an atom, the number of electrons and protons is equal, which makes an atom neutral as a whole. But when some of the particles are missing from an atom, i.e. when an atom loses electrons, it becomes positively charged whereas if it gains electrons it becomes negatively charged.
Charging of a body through friction(rubbing)
When two objects are rubbed against each other electrons are transferred from one object to another, making one object positive and the other negative.
For example, when we rub a rubber balloon with animal fur, the balloon which is made up of rubber, attracts the electrons from the animal fur. It makes the animal fur positively charged and the balloon negatively charged.
Universal law about charges is that like charges attract and unlike charges repel each other.
Electrostatic Force
The force of attraction or repulsion experienced by charged particles is known as electrostatic force.
What is a Static Electric Charge?
Those charged particles which do not move are called static charges. When two materials are rubbed against each other electrons are transferred from the less electronegative material to the more electronegative material. This transfer of electrons depends upon certain factors such as.
- Environmental Factor: Temperature and Humidity
- Nature: Properties of the material.
Transfer of Charges
Transfer of charges from one material to another takes place through two processes:
- Conduction: When the transfer of charges takes place through contact between a charged body and a conductor.
- Induction: When a charged body is brought close to a neutral body, it results in the shifting of charged particles inside the neutral body. The process of induction doesn’t require any contact. Induction happens between objects having less distance between them.
Conservation of Charge
The net charge in an isolated system remains constant, i.e. charges can neither be created nor destroyed.
For example: If a body having a +3C charge is brought in contact with a body having a -2C charge conduction takes place, and the net charge becomes +1C. In this case, the +2C charge is neutralized by -2C charge, but the net charge of the system remains constant, i.e. +1C.
Electroscope
It is a device used to detect if a body is charged or not.
It consists of a vertical metal rod, usually brass, from the end of which hang two parallel strips of thin, flexible gold leaf. When a charged object touches the brass disc, electric charges get transferred from the brass rod to the gold leaves. As a result, the gold leaves move away from each other, depicting the presence of charges.
Discharge and Earthing
When a charged object loses its charge, it is said to be discharged. Similarly, when a charged body loses charge and transfers it to Earth, the process is known as Earthing.
Earthing takes place when a charged body discharges into the Earth.
Why does lightning occur?
Lighter, positively charged particles form at the top of the cloud. Heavier, negatively charged particles sink to the bottom of the cloud. When the positive and negative charges grow large enough so that they come in contact, a giant spark is produced between the two charges within the cloud, which is called lightning.
We know that charge induction happens more in closer objects than in faraway objects. Tall buildings and trees have less distance from the clouds in comparison to shorter objects, so they are more prone to lightning.
Lighting carries a lot of electric charges which can be destructive. So there are some safety measures one should follow during a thunderstorm.
- Do not carry an umbrella during a thunderstorm.
- Do not get near any metal infrastructure like a pole or tower.
- Do not stay in open spaces like open grounds.
- Stay away from electrical wires telephone, cables, and metal pipes during a thunderstorm.
- Unplug all the electrical appliances in the house.
Tall buildings are protected from lightning by using a metallic rod having a height more than the building which is placed on the walls of the building during construction. In this safety measure, one end of the rod is in the air while the other end is buried inside the Earth so that if lightning strikes the building, the conductor carries these charges quickly to the ground.
Earthquakes
An earthquake is the shaking of the surface of the Earth. It is one of those natural phenomena which cannot be detected or predicted by scientists.
It occurs for a short time but can destroy life and property.
Causes of Earthquakes
The Earth is divided into different layers, i.e. core, mental, and crust. The outermost layer is divided into seven tectonic plates. These tectonic plates are always in motion. As they move, they collide with each other and cause disturbances. These disturbances are called an earthquake.
It can be caused by other factors such as volcanic eruptions, nuclear explosions, etc.
Seismic Zones:
Earthquakes occur when tectonic plates collide. So the areas which are most prone to earthquakes are near the boundaries of tectonic plates. These zones are known as weak zones, fault zones or seismic zones.
Richter Scale
It is a scale that is used to determine the strength (magnitude) of an earthquake is known as the Richter Scale.
Seismic Waves: Earthquake produces waves on the Earth’s surface. These surfaces are called seismic waves.
Focus: Focus on the point inside the Earth’s surface where an earthquake originates.
Epicentre: The epicenter is the point on the Earth’s surface above the focus.
Seismograph: It is a device that records seismic waves. It consists of a pendulum which is connected to a pen. When an earthquake occurs, the pendulum pen records the seismic waves on paper.
How can people protect themselves from an earthquake?
- Hide under a table until the earthquake stops.
- Do not stay close to heavy and tall objects.
- Find a place that has no tall buildings or trees around.
- If a person is inside a car or a bus, they should drive slowly to a definite place and be inside until the earthquake stops.
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