Resistors are the basic components of any circuit. Resistors can be used to limit current or voltages, as per the requirements. Resistors are passive devices .Active device is a device which generally needs a separate power (apart from the signal) to operate, while a passive device does not need any separate power source to operate..Passive devices may be device which may consume energy.
Unit of Resistance: Resistance is measured in "ohm" (Symbol : Ω) , and is given by R=V / I ,where V = Voltage and I = Current.
The most common uses of resistors are:
Limit the flow of current or voltage :
Here, a 9 Volt source is connected to an LED, but the LED is rated with 2-3 volts. So, a resistor is used in series such that the resistor drops the voltage by 7 volts and then it is passed through the LED.
Resistors are used to direct current flow to particular parts of the circuit:
Pull Up and Pull Down Resistors:
The purpose of these resistors is to force an output or input to go to a defined state.
A pull-up resistor weakly "pulls" the voltage of the wire it is connected to towards its voltage source level when the other components on the line are inactive.
For example, in the below circuit diagram, if switch is open, Vout is '1' due to pullup resistor and if switch is closed, Vout is '0' due to pullup resistor.
Resistance can be created by using coils, but now a days, small cylindrical resistance, made of ceramics/carbon etc are used, because coils generate large amount of heat and are bulky, as compared to ceramic resistors.
RESISTANCE CALCULATION:
Calculation of Resistance by color coding:
Resistance can be calculated by looking the color coding on the surface of the resistor. There are mainly 4 color rings on a resistor. First and second ring gives the first two digits of the resistance value (If there are total five rings, then first three rings gives the first three digits of the resistance). Third ring is the multiplier and fourth ring is the tolerance.
Alternatively, you can also get the resistance value with the help of multimeter, by connecting both the terminals of the resistor and rotating the multimeter knob to resistance calculator.
If you still need a simple way for the calculation of the resistances, then here's a simple application created by me, which gives you the Resistance Value, when you input the specified colors. Here's the screenshot. Download from the below link...
--Download Resistance Calculator app for Windows--
Unit of Resistance: Resistance is measured in "ohm" (Symbol : Ω) , and is given by R=V / I ,where V = Voltage and I = Current.
The most common uses of resistors are:
Limit the flow of current or voltage :
Here, a 9 Volt source is connected to an LED, but the LED is rated with 2-3 volts. So, a resistor is used in series such that the resistor drops the voltage by 7 volts and then it is passed through the LED.
Resistors are used to direct current flow to particular parts of the circuit:
Pull Up and Pull Down Resistors:
The purpose of these resistors is to force an output or input to go to a defined state.
A pull-up resistor weakly "pulls" the voltage of the wire it is connected to towards its voltage source level when the other components on the line are inactive.
For example, in the below circuit diagram, if switch is open, Vout is '1' due to pullup resistor and if switch is closed, Vout is '0' due to pullup resistor.
Resistance can be created by using coils, but now a days, small cylindrical resistance, made of ceramics/carbon etc are used, because coils generate large amount of heat and are bulky, as compared to ceramic resistors.
RESISTANCE CALCULATION:
Calculation of Resistance by color coding:
Resistance can be calculated by looking the color coding on the surface of the resistor. There are mainly 4 color rings on a resistor. First and second ring gives the first two digits of the resistance value (If there are total five rings, then first three rings gives the first three digits of the resistance). Third ring is the multiplier and fourth ring is the tolerance.
Alternatively, you can also get the resistance value with the help of multimeter, by connecting both the terminals of the resistor and rotating the multimeter knob to resistance calculator.
If you still need a simple way for the calculation of the resistances, then here's a simple application created by me, which gives you the Resistance Value, when you input the specified colors. Here's the screenshot. Download from the below link...
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