# ELEC1111 - Electrical Circuit Fundamentals

**Study Level and UNSW Handbook**

Undergraduate - ELEC1111

**Requisite Courses**

None

**Contents**

# Overview

This course is the UNSW's introductory course into the world of electrical engineering.

# Concepts

## Fundamentals

Electrical Engineering stems from the various discoveries and efforts of scientists from the past

### Physics Basis

Electrical engineering stems from the physics of electromagnetism. Further introduction of electromagnetism is covered in PHYS1231 and the engineering application of electromagnetism in ELEC3115.

#### The Systems of Units

The System of Units refers to the *International System of Units* which is usually abbreviated as **SI**. The SI system

#### The Electric Charge

##### Current

Current by definition is the change in electric charge over the change in time.

Furthermore, the unit of current is amperes
\(\mathrm{A}\)
which is defined as 1 coulumb per 1 second for 1 ampere.

\begin{equation}
1\mathrm{A}=1\frac{\mathrm{C}}{\mathrm{s}}
\end{equation}

Common notations for currents in electrical engineering

\(I\)
: Constant current

\(i(t)\)
: Instantaneous or time-dependent current. It should be further noted that
\(i(t)\)
can be simplified as
\(i\)
. However, this simplification can lead to confusion with complex numbers which uses
\(i\)
as the symbol for imaginary numbers. As a result, it is common to see the imaginary symbol,
\(i\)
, be represented as
\(j\)
in electrical engineering. In the context of ELEC1111 and ELEC2134, the use of
\(j\)
is highly preferred over use of
\(i\)
due to convention.

It is common in