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What is Electric Charge
It is the basic property of matter
It causes attraction and repulsion in matter in presence of other matter
The amount of electricity contained in an object is called Electric Charge
It is denoted by Q.
What are Different Types of Charges
There are 2 types Of Charges
- Positive Charge
- Negative Charge
Important Property of Electric Charge
There are 2 important properties of Electric Charge
Unlike Charges Attract Each Other
So Positive Charge Attracts Negative Charge
Like Charges Repel Each other
(2 Positive Charges Repel each other or 2 Negative Charges Attract Each Other)
What is Charge on Different Parts of Atom
We know that Atom is made up of Protons, Neutrons and Electrons
| Parts Of Atom | Charge |
| Protons | They have Positive Charge |
| Electrons | They have Negative Charge |
| Neutrons | They have no Charge |
No charge In the green balls in the image showing laws of attraction and repulsion
Note-
If an item has equal number of Protons and Electrons, they would cancel each other, and the item would have no Charge
If it has More Protons than Electrons, it is Positively Charged
If is has More Electrons than Protons, it is Negatively Charged
What is Electric Current
It is the flow of Electric Charges in Conductor
It is the amount of Electric Charge flowing in a body in 1 Second
It is denoted by I.
Formula for Electric Current
Electric Current = Electric Charge/Time
I = Q/t
What is SI unit of Electric Current
It is measured in Ampere. It is denoted by A.
As
Electric Current = Electric Charge/Time
So
1 Ampere = 1 Coulomb/1 Second
What are Different Units of Electric Current?
It is measured in Ampere, Milliampere and Microampere
Ampere
It is the SI Unit of Electric Current
It is named after French Scientist Andre Marie Ampere
As Electric current = Electric Charge/Time
So 1 Ampere = 1 Coulomb/1 Second
One ampere is defined as the current produced when a charge of 1 coulomb flows for 1 second.
Milliampere
It is smaller unit of Electric Current
1000 Milli Ampere = 1 Ampere
1 Milliampere = 1/1000 Ampere
1 Milliampere = 10 -3 Ampere
1 mA = 10 -3 A
Microampere
It is even smaller unit of Electric Current
10,00,000 Miliampere = 1 Ampere
1 Milliampere = 1/1000000 Ampere
1 Microampere = 10 -6 Ampere
1 μA = 10 -6 A
Electric Current is flow of electrons(negatively charged particles)
Electric Current moves from negative Side of battery to positive Side of battery
How does Electric Current Flow in a Circuit Diagram
In Circuit Diagram, it is represented that
Electric Current flows From Positive end to negative end
This is because when electricity was first discovered, the existence of electrons was not known
However, in reality, it is the opposite.
Electric Current flows from Negative end of battery to positive end
How is Electric Current Measured?
it is measured with the help of Ammeter
This instrument is connected in a series in an electric circuit
In circuit diagram, it is denoted by
Questions
Q2 Page 200 - Define the unit of current.
Q3 Page 200 - Calculate the number of electrons constituting one coulomb of charge.
Example 12.1 - A current of 0.5 A is drawn by a filament of an electric bulb for 10 minutes. Find the amount of electric charge that flows through circuit.
Question - A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly
(a) 10 20
(b) 10 16
(c) 10 18
(d) 10 23
