The earth gifts us with abundant natural phenomena to witness. Some being fascinating and constructive phenomena like rainbows, the water cycle, etc., while others are destructive in nature and cause adversity like cyclones, storms, etc. In the chapter Some Natural Phenomena Class 8, we will look at two destructive natural phenomena, how they occur, and ways to protect ourselves or decrease destruction caused by them. Read this blog to find the study notes for Class 8 Some Natural Phenomena, important questions, solutions and more.
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Almost all of us have seen sparks when the wire is loose or when a plug is loosely attached to the socket. These are electrostatics that occurs on a small scale. Now imagine an electric discharge on the entire world. It is bound to be huge and carries an immense charge called lightning. In this chapter Some Natural Phenomena Class 8, let’s see the history of sparks and other activities to understand the nature of electric charges.
Charging by Rubbing
The history of sparks can be traced back to 600 B.C. when an American scientist Benjamin Franklin, showed that the sparks caused by rubbing fur and amber or the polyester clothes when rubbed against the body, were the same as lighting. When we rub 2 objects or elements, the electrons are transferred from one object to the other which gives rise to static electricity. If an element loses electrons, it becomes positively charged. While if an element gains electrons it becomes negatively charged.
Example of Charged Objects:
- When we rub a plastic comb with dry hair, it obtains a small amount of charge and becomes negatively charged. The comb then attracts small pieces of paper by transfer of charge.
Some Natural Phenomena Class 8 Activities: Types of Charging and their interaction
For the chapter Some Natural Phenomena Class 8, students can perform the activities mentioned. By performing the following activities, you can understand the types of charging and their interaction.
|Activity 1||Hang two inflated balloons in such a way, so as to avoid constant between them. Rub both the balloons with a woolen cloth and release them.||You will notice that both the balloons repel each other.|
|Activity 2||Take two used pen refills. Rub one with polythene and put it carefully in a glass. Rub the other refill and bring it closer to the first one.||In the same way, both the refill pens repel each other.|
However, if we bring the balloon close to the refill pen, the two objects attract! This proves that:
- Similar Charges repel each other.
- Opposite charges attract each other.
Transfer of Charge
The following activity for the chapter Some Natural Phenomena Class 8 will help students understand the transfer of charge and earthing.
Take an empty jam bottle and cardboard bigger than the mouth of the bottle. Make a hole in the cardboard and insert a metal clip. Twist the metal clip and attach two pieces of aluminum foil to hang them on the paper clip. Make sure that the metal clip is perpendicular. Now take a charged refill by rubbing it with polythene and touch the end of the metal clip. You will notice that both the aluminum strips repel each other. A similar case is seen when you touch other charged bodies with the metal clip.
Therefore we conclude that electric charge can be transferred from one object to the other through a metal conductor (metal is a good conductor of electricity). Since both the foil strips get the same type of charge they become wide open. The device called Electroscope is designed based on this idea which helps us check if an object is carrying charge or not.
In the same activity, When you touch the metal clip with your hands, you will notice that the foil strips come back to their original position and no longer repel. This is because the foil strips lose electric charge through our hands and our bodies into the earth. This phenomenon is called Earthing.
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What is Lightning?
Now that we know about the various charges and how they are produced, let’s understand the story of lightning.
Lightning is caused by the transfer of charge from each cloud, eventually to the earth. It is a bright streak of light which is caused by an electric spark that takes place in the sky due to the strong movements of the air current (upward movement) and water droplets (downward movement).
Safety measures during a lightning
This massive streak of light is extremely strong with a charge of 300 million Volts (as compared to the 120 volts at our homes) and is 4 times hotter than the sun’s surface. If struck by lightning, it can cause the destruction of property and the death of living beings. It is necessary that you take safety measures.
- During a thunderstorm or lighting, avoid being in an open space, as it can cause direct contact with lightning.
- As soon as you hear the first thunder hit, make sure you are in a safe space like a building or a house.
- Do not use open vehicles like motorbikes or cycles during a thunderstorm.
- Do not leave the house immediately after the thunderstorm and lighting ends. Wait for a while and then leave the safe space.
|Safety Measures Outside||If you are travelling by bus or car, roll the windows up and keep the doors closed. Avoid open fields and gardens. Make sure you are away from tall trees. If stuck in a forest area, take shelter under the smaller trees. Stay away from poles and do not use umbrellas during a thunderstorm.|
|Safety Measures at home||Do not use electric phones or appliances during a thunderstorm. Avoid telephones and unplug all electric appliances. (Washing Machines, TV, Computers, etc)Do not take a bath during a thunderstorm to not come in contact with running water.|
Now, let’s see the other destructive phenomenon- Earthquake, What causes an earthquake, and protection during an earthquake for the chapter Some Natural Phenomena Class 8.
What is an Earthquake?
The sudden shaking (trembling) of the earth when there is some disturbance inside the earth’s crust is called an Earthquake. This phenomenon occurs many times with some being unnoticed depending on its intensity. However, some earthquakes are very intense and can cause the destruction of lives and properties, some even leading to tsunamis and floods.
The earth’s surface is divided into 3 parts: crust, mantle, inner core, and outer core. The fragmented outer layer has many plates which keep brushing against each other and often collide. An earthquake is caused due to the movement of plates in the outermost crust of the surface of the earth.
Other causes of earthquakes include:
- Tremors: Tremors other causes of earthquakes which are experienced when a volcano erupts or a nuclear explosion occurs or a meteor hits the earth.
- Seismic zones: Since earthquakes are caused by the movement of pilates, the areas that lie towards the boundaries are at greater risk due to the presence of weak zones, fault zones which are also called Seismic Zones.
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What is the Richter Scale?
A scale that is used to measure the magnitude of an earthquake is called the Ritcher scale. A magnitude of more than 7 on the Richter scale indicates a destructive earthquake. (For example, Bhuj and Kashmir earthquakes had a magnitude of more than 7.5).
Protection During an Earthquake
Since earthquakes are unpredictable, it is necessary that we know the do’s and dont’s while facing the phenomena. For protecting ourselves during an earthquake, let’s see the safety measures under the chapter Some Natural Phenomena Class 8.
- Buildings that are prone to the risk of an earthquake must be constructed in such a manner so that they handle major tremors.
- People must consult architects and engineers to build such a building.
- It is better to use timber rather than heavy construction material in high seismic areas.
- Make sure the cupboards are fixed and be careful of hanging frames and water heaters so as to prevent them from falling during an earthquake.
- Make sure the building has fire fighting equipment.
|Protection during an earthquake at home||Hide under the take if an earthquake occurs.Maintain distance from heavy objects|
Stay on your bed and protect your head with a pillow.
|Protection during an earthquake outside||Find a clear place with no tall buildings or trees.If you are in a vehicle like a car or a bus, do not leave until the tremor stops.|
We hope that you have understood the causes and protection of lightning and earthquakes for the chapter Some Natural Phenomena Class 8. Click here to check out more such Leverage Edu study notes on Class 8 syllabus.