Chapter 15 Some Natural Phenomenon Class 8 Notes | EduRev

Science - Short Notes for Class 8th

Created by: Sushil Solanki

Class 8 : Chapter 15 Some Natural Phenomenon Class 8 Notes | EduRev

 Page 1


Chapter 15 Some Natural phenomenon 
1. Lightening –  
It is caused by the charges that accumulates in the clouds. When two charged clouds collide, it produces 
lightening. 
If we take off our clothes in dark similar sparks can be seen.  
 
An object can be charged by rubbing it with certain objects. 
For e.g. A scale can be charged by rubbing with hair. The charged scale can attract pieces of paper. 
 
 
How does Lightening occur –  
During thunderstorm the positive and the negative charge accumulates of the upper end and the lower 
end of the cloud respectively. The ground also becomes positively charged. Air is an insulator, however 
the amount of charge is so much that it passes through the air to the ground.  
The passing current is visible is an electric streak accompanied by loud sound. 
 
 
 
 
 
 
 
 
 
 
 
Lightening  
 
 
 
    Ground               ++++++++++++++++++++++++++++++++++++++++++++ (Positively charged) 
 
Types of charges: 
a. Positive charge 
b. Negative charge 
Electroscope is used to detect charge on an object. 
Earthing – Process of transmitting charge to the Earth to lose extra charge from an object or circuit is 
known as Earthing. 
Discharge – the process of losing charge is known as discharge. 
 
Do’s and Don’ts during Lightening 
? Move to a safe area as soon as you hear thunder 
++++++++++++++++++++   (Positive Charge) 
 
-  - - - - - -- - - - -  - - - - - - - (Negative Charge) 
Page 2


Chapter 15 Some Natural phenomenon 
1. Lightening –  
It is caused by the charges that accumulates in the clouds. When two charged clouds collide, it produces 
lightening. 
If we take off our clothes in dark similar sparks can be seen.  
 
An object can be charged by rubbing it with certain objects. 
For e.g. A scale can be charged by rubbing with hair. The charged scale can attract pieces of paper. 
 
 
How does Lightening occur –  
During thunderstorm the positive and the negative charge accumulates of the upper end and the lower 
end of the cloud respectively. The ground also becomes positively charged. Air is an insulator, however 
the amount of charge is so much that it passes through the air to the ground.  
The passing current is visible is an electric streak accompanied by loud sound. 
 
 
 
 
 
 
 
 
 
 
 
Lightening  
 
 
 
    Ground               ++++++++++++++++++++++++++++++++++++++++++++ (Positively charged) 
 
Types of charges: 
a. Positive charge 
b. Negative charge 
Electroscope is used to detect charge on an object. 
Earthing – Process of transmitting charge to the Earth to lose extra charge from an object or circuit is 
known as Earthing. 
Discharge – the process of losing charge is known as discharge. 
 
Do’s and Don’ts during Lightening 
? Move to a safe area as soon as you hear thunder 
++++++++++++++++++++   (Positive Charge) 
 
-  - - - - - -- - - - -  - - - - - - - (Negative Charge) 
? Wait for some time before coming out after the thunderstorm is over 
? Stay away from open areas, tall trees, open vehicles and poles. 
? Avoid bathing during thunder. 
? Do not use electrical appliances. 
Lightening Conductors 
It is a device fitted on the top of a building, which runs through the building into the ground. If lightening 
falls on the building it is carried to the earth (Earthing) by the lightening conductor and protects the building 
from any damage. 
 
 
2. Earthquake 
Sudden shaking of Earth that occurs due to disturbances in the Earth’s crust is known as Earthquake. 
The intensity of Earthquake is measure by Richter Scale. 
 
Cause: 
The Earth is formed of three main layers – the upper most Crust, middle layer is known as mantle and 
the lowermost layer is the core. 
Earth’s crust is made up of several plates also called tectonic plates and is not a single piece of land as 
visible from the outside. These plates are in constant motion floating over the semi-liquid mantle. The 
collision of these plates leads to vibrations, which are felt as Earthquake. 
 
Earthquakes are more likely to occur at the boundaries of these plates, and hence these boundaries are 
known as seismic or fault zones. Kashmir, western and central Himalayas lies on the boundary of these 
plates and are one of the most threatened areas of Earthquake. 
 
Preventive measures in Earthquake prone areas: 
1. The houses should be built with mud or timber to reduce damage if the roof falls. 
2. The cupboards should be fixed to the walls to avoid falling during an Earthquake. 
3. All building should have firefighting equipment, as there may be incidences of fire during 
Earthquake. 
4. Carefully hang the wall clocks and photo frame as they may fall and cause injury. 
 
Do’s and Don’ts during Earthquake: 
1. Hide under a table until the shaking stops. 
2. Stay away from heavy objects. 
3. Find an open area away from buildings and trees. 
4. Stay in the car or bus and take it to an open area. 
 
 
 
.  
 
 
Page 3


Chapter 15 Some Natural phenomenon 
1. Lightening –  
It is caused by the charges that accumulates in the clouds. When two charged clouds collide, it produces 
lightening. 
If we take off our clothes in dark similar sparks can be seen.  
 
An object can be charged by rubbing it with certain objects. 
For e.g. A scale can be charged by rubbing with hair. The charged scale can attract pieces of paper. 
 
 
How does Lightening occur –  
During thunderstorm the positive and the negative charge accumulates of the upper end and the lower 
end of the cloud respectively. The ground also becomes positively charged. Air is an insulator, however 
the amount of charge is so much that it passes through the air to the ground.  
The passing current is visible is an electric streak accompanied by loud sound. 
 
 
 
 
 
 
 
 
 
 
 
Lightening  
 
 
 
    Ground               ++++++++++++++++++++++++++++++++++++++++++++ (Positively charged) 
 
Types of charges: 
a. Positive charge 
b. Negative charge 
Electroscope is used to detect charge on an object. 
Earthing – Process of transmitting charge to the Earth to lose extra charge from an object or circuit is 
known as Earthing. 
Discharge – the process of losing charge is known as discharge. 
 
Do’s and Don’ts during Lightening 
? Move to a safe area as soon as you hear thunder 
++++++++++++++++++++   (Positive Charge) 
 
-  - - - - - -- - - - -  - - - - - - - (Negative Charge) 
? Wait for some time before coming out after the thunderstorm is over 
? Stay away from open areas, tall trees, open vehicles and poles. 
? Avoid bathing during thunder. 
? Do not use electrical appliances. 
Lightening Conductors 
It is a device fitted on the top of a building, which runs through the building into the ground. If lightening 
falls on the building it is carried to the earth (Earthing) by the lightening conductor and protects the building 
from any damage. 
 
 
2. Earthquake 
Sudden shaking of Earth that occurs due to disturbances in the Earth’s crust is known as Earthquake. 
The intensity of Earthquake is measure by Richter Scale. 
 
Cause: 
The Earth is formed of three main layers – the upper most Crust, middle layer is known as mantle and 
the lowermost layer is the core. 
Earth’s crust is made up of several plates also called tectonic plates and is not a single piece of land as 
visible from the outside. These plates are in constant motion floating over the semi-liquid mantle. The 
collision of these plates leads to vibrations, which are felt as Earthquake. 
 
Earthquakes are more likely to occur at the boundaries of these plates, and hence these boundaries are 
known as seismic or fault zones. Kashmir, western and central Himalayas lies on the boundary of these 
plates and are one of the most threatened areas of Earthquake. 
 
Preventive measures in Earthquake prone areas: 
1. The houses should be built with mud or timber to reduce damage if the roof falls. 
2. The cupboards should be fixed to the walls to avoid falling during an Earthquake. 
3. All building should have firefighting equipment, as there may be incidences of fire during 
Earthquake. 
4. Carefully hang the wall clocks and photo frame as they may fall and cause injury. 
 
Do’s and Don’ts during Earthquake: 
1. Hide under a table until the shaking stops. 
2. Stay away from heavy objects. 
3. Find an open area away from buildings and trees. 
4. Stay in the car or bus and take it to an open area. 
 
 
 
.  
 
 
 
Read More

Share with a friend

Complete Syllabus of Class 8

Dynamic Test

Content Category

Related Searches

pdf

,

Viva Questions

,

Exam

,

Free

,

Important questions

,

Objective type Questions

,

Semester Notes

,

Summary

,

practice quizzes

,

MCQs

,

study material

,

Chapter 15 Some Natural Phenomenon Class 8 Notes | EduRev

,

past year papers

,

mock tests for examination

,

ppt

,

Chapter 15 Some Natural Phenomenon Class 8 Notes | EduRev

,

Chapter 15 Some Natural Phenomenon Class 8 Notes | EduRev

,

video lectures

,

Extra Questions

,

shortcuts and tricks

,

Sample Paper

,

Previous Year Questions with Solutions

;