Some Natural Phenomena NCERT Science Class VIII Chapter 15 Summary Note

When we take off clothes in dark, we see a spark and crackling sound. Because
- Our body gets rubbed with clothes. 
- This produces charges. 
- When charges meet, they cause spark and crackling sound. 

Charged object
Object having electric charge. 
Example- Rubbed balloon

Electric charges are generated by rubbing. 

Types of charges- 
(a) Positive charge 
(b) Negative charge 

Interaction between charges
-Like charges repel each other. 
-Unlike charges attract each other. 

It is a convention to call the charge acquired by a glass rod when it is rubbed with silk as positive. 
The another kind of charge is said to be negative. 

Static charge 
Charge that do not move. 

Electric current
Movement of charges , is electric current. 


Electroscope 
A device that test whether an object is charged or not, is called electroscope. 


Comments

Post a Comment

Popular posts from this blog

Fibre to Fabric NCERT CBSE CLASS 7 Science Online Test/Quiz

Fibre to Fabric  NCERT CBSE Class 7 Online Test/Quiz for Fibre to Fabric  Online test for "fibre to fabric" consists of ten questions, all having four alternatives. You have to choose the correct option. After attempting all questions, enter your name, class, roll no and email id. Email id is asked because through that results will be share to you.  And at last don't forget to submit your answers. After submission you can see your results too.  Enjoy taking test.  Topic- Fibre to Fabric NCERT CBSE Science Class 7 Loading…
Read more

Light NCERT Science Class 8 Summary Note

Image
What Makes Things Visible   When light from an object enters our eyes, then we see the object.  The light may have been emitted or reflected by the object.  Mirror   Highly polished surface is called mirror.  Reflection Bending back of light ray after falling on a surface, is called reflection.  Incident ray The light ray which strikes any surface, is called incident ray.  Reflected ray  The ray that comes back from the surface after reflection, is called as reflected ray.  Normal Line perpendicular to surface at point of incidence of light ray, is called normal.  Angle of incidence The angle between normal and incident ray, is called angle of incidence.  Angle of reflection The angle between normal and reflected ray, is called angle of reflection.  Laws of reflection (i) The incident ray, the normal at the point of incidence and the reflected ray, all lie in the same plane.  (ii) The angle of incidence is always equal to the angle of reflection.  Nature of Images formed by Plane Mirro
Read more

Chemical Effects of Electric Current NCERT Summary Class VIII Science Chapter 14

Image
Good Conductor The substance through which electricity can pass is called good conductor.  Examples - Copper, Aluminum Poor conductor The substance through which electricity can not pass is called poor conductor. Examples - Rubber, plastic etc.  Tester A device that test conductance of a substance, is called tester.  Solutions of acids, bases and salts are generally good conductor.  Chemical effects of Current Chemical reactions (effects) caused when electricity passes through a conducting liquid, is chemical effects of current.  How to recognize chemical reaction - Release of gas - Change of colour of solution - Release of heat - Formation of new substance In battery No. of terminals- 2 (positive and negative)  Positive terminal is also called Anode .  Negative terminal is also called cathode .  Solution  is called electrolyte .  Passing current through a solution What happens when electricity is passed through c
Read more