Complete guide on resistance
Resistor is an electronic component which oppose the flow of electrons. The resistor can possibly be made up of either, by a carbon or a particular conductive(or resistive ) element. And the carbon ratio changes the flow of current through resistor.
More carbon filling means, less resistance value, means more flow of electric current. Carbon is conductor so when we increase carbon in resistor While making resistor, a carbon film is wrapped around an insulator. and more number of wraps come up with higher number of resistance because of higer insulating layer
Above video will give you an idea about how resistor actually works, and according to each resistance reading, If you break that led into a piece you can make your own resistor.
Current and Resistor "ALWAYS Fights".
Electric Current and resistance always fights with each other. If the Electric current value is higher than resistor operating range then resistor might get burn (Resistor will lost the fight).
So, to make sure resistor should survive in this battle. We should carefully examine, That what value of resistance( power-rating ) we are using in front of Current, so that we can prevent our resistor for getting burn in circuit.
POWER RATING define as the Power of any component above which it get destroyed.
when you go to market, For purchasing Resistor of any value, of any type (mentioned in type of resistor), you must have to examine its POWER RATING very carefully. Because once you operate that resistor above its Power-rating limit, Its burn and get destroyed.
It is clearly visible that tiny sized resistor have less capability to stand in front of large current, Let suppose R1 resistor have 330ohm of 1/2watt power rating and R2 resistor have 550ohm of 1/4watt power.
To know, while operating this resistor, will being safe with your input voltage or current you need this formula :-
1. If you know voltage across resistor
2. If you know current through resistor.
Types of Resistor.
- Wire-wound resistors.
- Carbon-composition resistors.
- Film-type resistors.
1. Carbon film.
2. Metal film.
- Surface-mount resistors (chip resistors).
- Fusible resistors.
Wire wound resistor is a type of fixed resistor. This resistor is made by winding the resistive wire around the non-conductive core. The resistance depends on three factors.
⦁ The resistivity of the wire.
⦁ Length of wire.
⦁ Cross-sectional area.
Advantages of a wire-wound resistor:
⦁ Low cost.
⦁ High accuracy.
⦁ High stability.
⦁ Wide resistance range.
The disadvantage of a wirewound resistor is used only for low frequencies.
Some applications are given below;
⦁ Current voltage balancing
These resistors are most commonly used resistors in the 1960s and earlier. Nowadays Carbon Composition Resistor is rarely used because of its high cost and low stability. The resistance of the carbon composition resistor depends on three factors are given below,
⦁ Amount of carbon added.
⦁ Length of the solid cylindrical rod.
⦁ The cross-sectional area of the solid cylindrical rod.
The advantages of these resistors are its ability to face the high energy pulse.
The disadvantages of these resistors are:-
⦁ Poor stability.
⦁ generate high noise.
⦁ Low accuracy.
⦁ Absorption of water therefore increase or decrease the resistance.
Film type resistors.
1. Carbon film resistor:-
–These type of resistor are widely used in electronic circuit.Carbon film resistor is made from carbon film.This is actually a fixed type of resistor means it provides only a single resistor value. Here the carbon film plays the roles of resistive material.The resistance of carbon film resistor is depends on two factors, first thickness of carbon film layer and second is width of helical carbon film.There are some advantages of carbon film resistors.
⦁ Low tolerance.
⦁ Low cost.
⦁ Wide operating range.
2. Metal film resistor:-
–The metal film resistor is made from metal film.The resistance of metal film resistor is depends on two factors, first thickness of metal film layer and second is width of helical metal film.There are some advantages of metal film resistors.
⦁ Generates less noise as compare to carbon film resistor.
⦁ It contain low tolerance.
⦁ Low cost.
⦁ Long term stability.
⦁ Very small size.
Surface-mount resistors (chip resistors)
The surface-mounted resistor is also called a chip resistor. Chip resistor has normally 4 types that are :
1. Thick film chip resistor,
2. Thin-film chip resistor,
These chips are mainly used in the power circuit. The resistance of this chip is low and work in high resistance.
3. Chip jumper zero ohm chip resistor:-
These type of resistors are that resistor which contains zero or less than zero value. It works like a fuse.
4. Shunt chip resistor,
Shunt chip resistor works in high voltage resistor.These resistor are placed in DC to DC converter , battery tester circuit, detector circuit
It is a temperature-sensing device. Through thermistor, we can measure the temperature and also control the temperature. It is made up of semiconductor material. Its property is that when the temperature is increased, its resistance will increase or decrease. And the resistance will increase or decrease it will depend upon its semiconductor material properties.
Generally, a thermistor is of two types:
1. PTC(positive temperature coefficient)
If the thermistor is placed at that point where the temperature is increasing than according to this increase in temperature the resistance of thermistor will also increase and this type of thermistor is called PTC.
2. NTC(negative temperature coefficient)
If the thermistor is placed at that point where the temperature is increasing but the resistance of the thermistor is decreasing this type of thermistor is called NTC.
Generally, NTC is used in the thermistor.
Temperature range between -100degree to 400degree.