Digital Electronics & Computer Architecture
Courses
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My notes & review of Digital Electronics & Computer Architecture
Notes
Introduction
- The Ancient Greek work for amber is elektron. Thales of Miletus observed around 600 BC that rubbing amber attracted light objects.
- In 1600, English Philosopher William Gilbert was first to coin the term electricitus, behaving like amber, as he recognized this behavior in other materials.
- In 1746, the Leyden Jar was used to store high-voltage electric charge. In modern terms this is called a capacitor.
Electric Current
- In 1897, Joseph John Thomson discovered the electron by showing that cathode rays in a vacuum tube were made of tiny, negatively charged particles much smaller than atoms.
- Voltage is the electric potential difference between two points in a circuit.
- Electrons flow from negative charge (more electrons than protons) to positive charge (more protons than electrons). This flow is called current, flow of electrons from one point to another. We measure current in amps.
- “Holes” move in the opposite direction, positive to negative. This is also called the Electric Field, also called Conventional Current.
- The positive end is also called the “attractor” while the negative end is called the “source”.
- The resistance makes it difficult for electrons to move, limiting the amount of current that can flow. Measured in ohms.
- Ohm’s Law: \(I = \frac{V}{R}\)
- \(I\) = current (amperes)
- \(V\) = voltage (volts)
- \(R\) = resistance (ohms)