About Lesson
Unit: 1 Electrostatics
Chapter-01: Electric Charge and Fields
Chapter-01: Notes, Day 01
Day 01
Day 02
Electricity: The energy due to which matter gets property of attracting the things is known as electricity.
Electric Charge:
- Electric Charge is an intrinsic property of the elementary particles such as electrons and protons.
- Electric Charge is a scaler physical quantity.
- SI unit of Electric Charge is Coulomb (C).
Type of Electric Charge: There are two type of Electric Charge.
- Positive Charge (Proton)
- Negative Charge (Electron)
Properties of Electric Charge
- Like charges repel each other.
- Unlike Charge attracts each other.
Examples of Charge
S.No. | Positive Charge | Negative Charge |
1. | Glass rod | Silk cloth |
2. | Woollen cloth | Amber,ebonite,rubber rod |
3. | Woollen coat | Plastic seat |
4. | woollen carpet | Rubber shoe |
5. | Flannel or cat skin | Ebonite rod |
Gold Leaf Electroscope : A type of electroscope that consists of two gold leaves and is used for detecting the electrical charge of the body.
Particle | Symbol | Charge | Mass |
Electron | e– | -e = -1.6X10-19C | 9.1X10-31kg |
Proton | p+ | +e = +1.6X10-19C | 1.6725X10-27kg |
Neutron | n0 | 0 C | 1.6748X10-27kg |
Conductors: The substance which allow flow of electric charges through them easily are called as conductors.
Ex.: Iron, Gold, Silver etc. (All metals)
Insulators: The substances which do not allow the flow of electric charge through them are called as insulators or bad conductors.
Ex. Wood, Rubber, Glass, Plastic etc.
- Insulators are also called as “Dielectries”.
Electrostatic Induction: When a charged conductor is brought near to an uncharged conductor,then opposite charges are produced at the near end and similar charges are on the far end of uncharged conductor. This phenomenon is called electrostatics induction.
Basic Properties of Electric Charge:
Additivity: The net charge present on a system is always equal to the algebric sum of all charge present in it.
Quantization: The quantity of charge on a substance is always integer multiple of charge on electron. q = ± ne
Conservation of Charges: According to principal of conservation of charges. the net charge present on an isolated system remains conserved.
Difference Between Electric Charge and Mass
S.No. | Electric Charge | Mass |
1. | Electric charge may be positive,negative or zero. | Mass of body is always positive. |
2. | Charge is quantize q=±ne | Quantization of mass is yet to beproved. |
3. | Electric charge is always conserved. | Mass is not conservedas it can be chargedinto energy and vice-versa |
4. | Force between charges can be attractive orrepulsive whether they are unlike or a like. | The gravitational force between two massesis always attractive. |
5. | Charge present on a body does not dependon the velocity of the body. | Mass of a body increases with its velocityaccording to the relativistic mass variation. |