Charge and Current This topic introduces fundamental electrical concepts essential for understanding the behavior of electric circuits. We will explore electric...
This topic introduces fundamental electrical concepts essential for understanding the behavior of electric circuits. We will explore electric charge, current, and basic electrical principles.
Electric charge is a property of subatomic particles, with two types: positive and negative. The unit of charge is the coulomb (C). The law of conservation of charge states that charge can neither be created nor destroyed; it can only be transferred from one object to another.
Current is defined as the rate of flow of electric charge. It is measured in amperes (A). The relationship between current (I), charge (Q), and time (t) is given by the equation:
I = Q/t
This equation indicates that the current is equal to the total charge flowing through a conductor divided by the time it takes for that charge to flow.
In circuits, current is often described as flowing from the positive terminal to the negative terminal, known as conventional current. However, in reality, it is the negatively charged electrons that flow from the negative terminal to the positive terminal.
Materials can be classified as conductors or insulators. Conductors, such as metals, allow electric charge to flow easily due to the presence of free electrons. Insulators, like rubber or glass, do not allow charge to flow freely.
The mechanism of electrical conduction in metals involves the movement of free electrons. When a potential difference is applied across a metal conductor, free electrons gain energy and drift towards the positive terminal, creating an electric current.
Understanding basic circuit symbols is crucial for analyzing electrical circuits. Common symbols include:
These symbols help in constructing and interpreting circuit diagrams.
Problem: A charge of 12 coulombs flows through a circuit in 3 seconds. What is the current?
Solution:
The current flowing through the circuit is 4 amperes.