What is Load Resistor or Load Resistance? Examples, Use

What is a Load Resistor?

A load resistor is a simple resistor that is used as a load with an electrical or electronic circuit. The main purpose of using a load resistor is to increase or decrease the overall load resistance of the circuit. There may be many objectives for using a load resistor. Such as to test a power circuit variable load resistance can be used to check the performance of the power generation circuit at the different loads. Basically, the load resistor consumes the electrical power when it is used in a circuit. 

There are mainly three types of load we see in electrical or electronic circuits such as - resistive load, inductive load, and capacitive load. The load resistor is basically a resistive load. So the load resistor is not different from a normal resistor as it is used as a load to the output of the circuit, that is why it is called a Load Resistor.

The load resistor may be in two forms - fixed and variable. The fixed load resistor will consume a constant current and power whereas the variable load resistor provides varying resistance so the current consumption is also not constant, it will vary with the varying of resistance.

What is Load Resistance?

The resistance offered by a load to the power circuit is known as load resistance. The load resistance is not offered by a resistive load in fact all the loads have their own internal resistance. There is no practical pure inductive load or capacitive load. High load resistance causes low electrical current consumption and low load resistance causes high electrical current consumption. We know that the unit of normal resistance is the ohm. So the load resistance also be measured in ohm. For a higher load, it can be measured in kilo ohm.

Examples of Load Resistor or Load Resistance

1. The EOL resistor in the conventional fire alarm system is an example of a load resistor.

2. The internal resistance of the field coil of a DC Shunt generator is an example of load resistance.

3. In audio systems, the speaker's impedance acts as a load resistance.

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Load Resistor Power Consumption

Generally, the nature of the load resistor is passive and linear. That means it does not require any external supply to operate and it makes the current-voltage graph linear. The power consumption by a load resistor can be calculated by the multiplication of the internal resistance of the load resistor and the square of the current flowing through it. 

So, P = I^2R   where P = power

                                  I = current

                                  R  = Resistance

The power consumption also be calculated by another equation which is P = VI

Here, P = Power,  V = Voltage across the load resistor,   I = current flowing through the resistor

Load Resistor Use and Applications

1. A load resistor is used to ensure a minimum current flow in a circuit.

2. A load resistor is used to check the maximum power transfer in a circuit.

3. A load resistor is used for impedance matching.

4. A load resistor is used for more stability in the output of a circuit.

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• Resistance Reactance Difference, Effects, Example, Application
• Meaning of Capacitor Voltage Rating and Value in Specification
• Difference between ElectroMagnetic Coil and Heating Coil

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