Charge and Current This topic introduces fundamental electrical concepts, including electric charge , current , and basic electrical principles. Electric Charge...
This topic introduces fundamental electrical concepts, including electric charge, current, and basic electrical principles.
Electric charge is a property of subatomic particles, which determines their electromagnetic interactions. There are two types of charge: positive and negative. Like charges repel each other, while opposite charges attract.
The principle of conservation of charge states that the total electric charge in an isolated system remains constant. Charge can neither be created nor destroyed, only transferred from one object to another.
Conventional current is defined as the flow of positive charge. It flows from the positive terminal to the negative terminal of a power source. In reality, the flow of charge in metals is due to the movement of electrons, which are negatively charged particles.
Current is defined as the rate of flow of electric charge. It can be mathematically expressed as:
I = Q/t
where I is the current in amperes (A), Q is the charge in coulombs (C), and t is the time in seconds (s).
Materials that allow the flow of electric charge are called conductors, while those that do not are known as insulators. Metals, such as copper and aluminum, are excellent conductors due to the presence of free electrons that can move easily through the material.
The mechanism of electrical conduction in metals involves the movement of free electrons. When a potential difference is applied across a conductor, these electrons gain energy and drift towards the positive terminal, creating a flow of current.
Understanding basic circuit symbols is essential for reading and constructing electrical circuits. Common symbols include:
Problem: A circuit has a current of 2 A flowing for 5 seconds. How much charge has passed through a point in the circuit?
Solution:
Thus, 10 coulombs of charge have passed through the circuit.