Resistance information

 RESISTANCE

The property of matter in an electric circuit which hinders the flow of electrons is called resistance. It is represented by 52 (ohm). Like- Mega Ojh (10), Micro Oda (10).

First symbol 

Second symbol 

Third symbol 

2.1 CLASSETICATION OF RESISTANCE

Resistances are based on the Odic value. These are named as short medium and high resistance.

1. Small resistance less than one Oda or one OZ

2.Resistance-greater than one and up to 100k) 3.High resistance-more than 100kOda

Method for measuring small resistance

 (1) Voltmeter by Ampere Meter

(1) by vinvapi (a comparison method unknown to the standard)

(C) Caldin bridge method

2

Is.

method for measuring resistance

(1) Ampere meter by Boltmeter

(d) Substitution Method

(1) Whitstone Bill

Method for measuring high resistance - Manger method

Triveer Meter and Voltmeter Method – This method is a simple method of small resistance, in this

R_ma resistance

V = high voltage

The DC supply passes through the variable resistance (R) to the ampere meter.

voltmeter reading

R₂ = Ampere meter reading

R Measured resistance

1. Carbon Film Resistance Carbon resistors are made by mixing different types of impurities in pure carbon. Taking them from an ohra. Made up to Mega Odha. At high current, they heat up quickly and their value also changes. Their weight is small in shape and the price is low. Used in phase testers, indicator lamps, electrical measuring instruments, etc. They are used in the adapter of CFL lamp.

2. Thermistor - Resistors whose value is dependent on temperature, they are used in them. Their value and capacity are very less. They are used in electronic work.

3. Metal Film Resistance - This carbon

Resistors are similar. Instead of carbon, they contain thin metal

The film goes up. Therefore, this resistance is higher than carbon resistors.

4. WIRE Wound Resistance 

 These are usually made by winding the wires of nichrome, eureka, magnin, tungsten, canthal. Spring type resistors are used as elements in heaters, electric irons, geysers, electric lamps, electric furnaces. They are also used in starters. These . watts to 100 watts. Their value ranges from 0.152 to 10 k52. The effect of temperature on these resistors is negligible.

5. Surface Mount Technique - The resistors used in surface mount technology are called surface mount resistors. This is a surface mount device with 2 terminals

Is.

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These resistors are rectangular in shape. There is a metallic region on both sides of this resistor (Figure 6), which serves to connect the face mount resistor to the printed circuit board with the help of solder. The top part of the resistor shown in the figure is coated with a non-conducting material. A resistive layer is made below it. The greater the length of this resistive layer, the greater the value of the resistance. Underneath this is a layer of high alumina ceramic material which provides stability to these types of resistors. The terminals of surface mount resistors are made of tin to increase soldering efficiency. The value of such resistors is in the range of 1052 to 10 M2 and the power dissipation is in the range of 0.0625 watts to 0.2500 watts. These resistors are made of linear, logarithmic and polynomial types.6.L.D.R. These are also known as light-sending resistance. Their value depends on the light falling on them. Their sub night lamps are in the automatic circuit of street lights.

7. V.D.R. This is called voltage dependent resistance. Their M depends on the voltage they receive. It shows low resistance at high voltage and high resistance at low voltage.

2.3 LAWS OF RESISTANCE

according to the law of resistance

1. The increase in resistance of a conductor is proportional to its length.

2 Resistance of a conductor is inversely proportional to its cross-sectional area

it happens.

3. The resistance of the conductor depends on the nature of the material.

4. The resistance of the conductor also depends on its temperature.

The resistance of any conductor depends on the following factors (1) The resistance of the conductor decreases in direct proportion to the length.

Is. If the length is increased then the resistance will increase and if the length is decreased then the resistance will also decrease. ie

R ∝l

where R= resistance of the conductor l= length of the conductor

                       

           resistance increases as the length of                                      the wire increases