Fundamentals of Electronics Engineering

  Passive and Active Electronic Components   •         An electronic circuit is comprised of different individual components, grouped as passive components and active components .   •         The components which do not in themselves provide gain are called passive components . Eg. resistors, capacitors and inductors.   •         Components which provide amplification or switching are called active components . Eg. diodes, transistors and Ics.   RESISTORS   •         A resistor is a two terminal electrical or electronic component that opposes an electric current by producing a voltage drop between its terminals in proportion to the current, that is Ohm’s law: V = IR . •         The electrical resistance is equal to the voltage drop V across the resistor divid...

  Concept of Alternating Current (AC) and Direct Current (DC)   An electric current is a flow of charged particles. Inside a copper wire, current is carried by small negatively-charged particles, called electrons . The electrons drift in random directions until a current starts to flow. When this happens, electrons start to move in the same direction. The size of the current depends on the number of electrons passing per second. Current is represented by the symbol I , and is measured in amperes , or ‘ amps ’, A. One ampere is a flow of 6.25 × 10 18 electrons per second past any point in a wire. That’s more than six million million million electrons passing per second. This is a lot of electrons, but electrons are very small and each carries a very tiny charge. In electronic circuits, currents are most often measured in milliamps , mA , that is, thousandths of an Ampere.   One terminal of a cell or battery is positive , while the other is negative . It is con...