Physics Study Guide/Electronics
Electronics is the application of electromagnetic (and quantum) theory to construct devices that can perform useful tasks, from as simple as electrical heaters or light bulbs to as complex as the Large Hadron Collider.
- 1 Electronics
- 1.1 Introduction
- 1.2 Circuits
- 1.3 Direct current and alternating current
- 1.4 Basic components
- 1.5 Ohm's law
- 1.6 Kirchoff's laws
- 1.7 Power
- 1.8 Resistors in series
- 1.9 Resistors in parallel
- 1.10 Superposition of sources
- 1.11 Capacitors
- 1.12 Inductances
- 1.13 Frequency-dependent circuits
- 1.14 Semiconductors
To discuss electronics we need the basic concepts from electricity: charge, current which is flow of charge, and potential which is the potential energy difference between two places. Please make sure these concepts are familiar before continuing.
The interest of electronics is circuits. A circuit consists of wires that connect components. Typical components are resistors, voltage sources and so on, which will be discussed later. A circuit can be open, when there is a break so that no current can flow, or it can be closed, so that current can flow. These definitions allow us to discuss electronics efficiently.
Direct current and alternating current
IF 'V' IS POTENTIAL DIFFERENCE APPLIED AT TWO ENDS OF CONDUCTOR AND 'I' IS CURRENT FLOWING THROUGH THE CONDUCTOR THEN 'I' IS DIRECTLY PROPORTION TO ITS 'V' V = I x R
Kirchoff's laws generally hold for direct current (DC) circuits, but fail when dealing with changing electric current and voltage such as alternating current (AC) or signal processing in combination with capacitors, inductors, and antennas.
Kirchoff's current law
The sum of all the currents entering and leaving any point in a circuit is equal to zero.
It is based on the assumption that current flows only in conductors, and that whenever current flows into one end of a conductor it immediately flows out the other end.
Kirchoff's voltage law
The sum of all the voltages around the circuit loop is equal to zero.
It is based on the assumption that there is no fluctuating magnetic field linking the closed circuit loop.
p=work done/time taken p=I*V (current * Voltage)
Resistors in series
Resistors in parallel
1/R = 1/R1+1/R2+1/R3+......
Superposition of sources
Current is the rate of flow of charge.
= Current [amperes - A]
= Charge [coulombs - C]
= Time [seconds - s]
Voltage is equal to current multiplied by resistance
Power is equal to the product of voltage and current
Electronics is the flow of current through semiconductor devices like silicon and germanium.
Semiconductor devices are those which behave like conductors at higher temperature.
Transistor, diode, SCR are some electronic devices.
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