Table of Contents
Charging of Insulators

Since charge cannot flow through insulators, neither conduction nor induction can be used to charge, insulators, so in order to charge an insulator friction is used. Whenever an insulator is rubbed against a body exchange of electrons takes place between the two. This results in appearance of equal and opposite charges on the insulator and the other body. Thus the insulator is charged.
For example rubbing of plastic with fur, silk with glass causes charging of these things.
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Reynolds Number
Last modified on:3 years agoReading Time:10MinutesWhat is Reynolds Number? The Reynolds number (Re) is a dimensionless parameter used in fluid mechanics to characterize the flow of a fluid (liquid or gas) around an object or through a conduit. It relates the inertial forces to the viscous forces in the fluid and helps determine the type of…
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Problems Based on Class 9 Science Chapter 10 Gravitation
Last modified on:5 years agoReading Time:6Minutes Q.1. An object weighs 10N when measured on the surface of the earth. What would be its weight when measured on the surface of the Moon? Q.2. Mass of an object is 10kg. What is its weight on Earth? Q.3. What is the mass of an object whose weight is…
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Problems Based on Universal Law of Gravitation
Last modified on:5 years agoReading Time:9MinutesQ.1. If the distance between two masses is increased by a factor of 4, by what factor would the mass of one of them have to be altered to maintain the same gravitational force? Q.2. The gravitational force between two objects is F. How will this force change when (i) distance…
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Electric Field Lines
Last modified on:3 years agoReading Time:5MinutesElectric Field Lines Electric charges create an electric field in the space surrounding them. It is useful to have a kind of “map” that gives the direction and indicates the strength of the field at various places. Field lines, a concept introduced by Michael Faraday, provide us with an easy way…
