What is Resistor
A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to provide a specific voltage for an active device such as a transistor.
All other factors being equal, in a direct-current (DC) circuit, the current through a resistor is inversely proportional to its resistance, and directly proportional to the voltage across it. This is the well-known Ohm's Law. In alternating-current (AC) circuits, this rule also applies as long as the resistor does not contain inductance or capacitance.
Resistors can be fabricated in a variety of ways. The most common type in electronic devices and systems is the carbon-composition resistor. Fine granulated carbon (graphite) is mixed with clay and hardened. The resistance depends on the proportion of carbon to clay; the higher this ratio, the lower the resistance.
Another type of resistor is made from winding Nichrome or similar wire on an insulating form. This component, called a wire wound resistor, is able to handle higher currents than a carbon-composition resistor of the same physical size. However, because the wire is wound into a coil, the component acts as an inductors as well as exhibiting resistance. This does not affect performance in DC circuits, but can have an adverse effect in AC circuits because inductance renders the device sensitive to changes in frequency.
Resistor Component's Symbol and Layout?
The symbol of a Resistor, as you can see that it is being label started with letter ''R'' meaning for Resistance and followed by a ''Mounted Code'', that code is the number of that resistor for easy identification and search reason on the whole structure of a PCB board. Then, also ob-course theResistance Value for test and check up procedures, like for example ''R4400 = 47K'' it means that Resistor number 4400 connected on that particular circuit's value is 47K or 47000 ohms. In that way we can easily trace and and test that component using a Multi-meter tester.
There are two types shown in here, The first one is Fixed Resistor and the other one with a line across to it is called Thermistor or Thermal Resistor.
Thermistor or Thermal resistor is a variable Resistor, meaning it's resistance value is changeable. Thermal defines to heat temperature, it is being change by a current or voltage flowing across to it. It also have a capability to shut off when a voltage or current drive it to a maximum temperature level.
While the Fixed Resistor, remains steady to it's resistance value.
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