Uses of Resistor

Download PDF

What is Resistance?

Bookmark added to your notes.
View Notes

Resistance is the speed breaker to the heavy traffic of current through the closed circuit. It has various applications and we can easily find at least one use of resistance in a circuit.

So, what happens is, when electrons start flowing through the circuit under the push, i.e.,  the potential difference, they collide with ions, and because of this electricity flow rate or the current decreases, and in one word, we denote it as resistance.  Also, the use of resistor generates heat in the circuit. 

On this page, we will understand what is the use of resistance and the application of resistance. 

How Does Resistance Works?

You spend your schooldays talking about conductors and insulators. You know what a conductor is, it is something that allows electricity to flow through it easily. The insulator is just the opposite – it is something that does not let the current flow through it easily. 

The difficulty to the current flow properties is a direct result of resistance – conductors like copper have a low resistance to the electric current flow, whereas insulators resist the flow of electric current to a large degree, i.e., have a large resistance. 

If we zoom into a wire to the atomic scale, we see that the wire is made of tiny atoms, just like in the image below:

(Image to be added soon)

When electrons flow through the wire, some of these pass easily through the gaps in the wire, while some of them hit an atom and bounce, sometimes electrons collide with each other; this makes the flow of electrons somewhat non-uniform and impeded (slow current flow rate) – this is resistance.

This also means that resistance depends on the type and properties of the material itself since the interaction of the electrons with the atoms depends on the size and packing of the atoms.

Resistance and Temperature

Considering a circuit model, when we heat the wire, we are supplying energy to the wire. This energy gets absorbed by the atoms which then start vibrating. These vibrations make it more difficult for the electrons to get through.

Now, we will write uses of resistors with their applications:

Application of Resistance

Now, we will write uses of resistors in points and then explain these one-by-one:

  • Circuit functions

  • LEDs and transistor

  • Dividing voltage

  • Heating

  • Frequency and timing

What is the Use of Resistance?

Following are the uses of resistors:

  1. Use of Resistor in Circuit Functions

There are different types of resistors that work according to the usage range. In this, we can set the resistance value by using a  kind of feature called a knob. 

Any changes in a resistance value affect the flow of current inside the circuit. 

The use of resistor in circuit functions are:

  • In controlling the speed of a motor, 

  • The pitch of a musical tone, and

  • The loudness of an amplifier.

  1. Use of Resistor in LEDs and Transistor

An overflow of the current through LEDs and transistors can be very dangerous, so an electric component called the resistance is employed to overcome this danger. 

Also, LEDs and transistors are very sensitive to electric current. So, the use of resistors in the circuit will help the LEDs and transistors, and other various types of semiconductors to function in the required current range ideal for them.

  1. Use of Resistor For Heating

Because of the collision of ions inside the material, some obstruction generates is the resistance, and this, in turn, produces a lot of heat when conducting current, 

We find the use of a resistor in a heater, toaster, microwave, electric stove, and many more heating appliances. 

In a light bulb, the metal filament (made of tungsten) glows white-hot due to the very high temperature produced from the resistance (slow electricity flow rate) when electricity is passed through it.

  1. Use of Resistance to Function in Particular Timing and at Specific Frequency

Various circuits use a resistor connected to a capacitor to access the timing source. Devices like light flashers, electronic sirens, blinking lights and many other circuits rely on this feature.

The devices mentioned above are used in airplanes and tall towers to work as a collision avoidance measurement. Here, these devices work on the phenomenon of filling up current to a certain time and then discharge light. The resistor decides whether how much current has to be passed at a particular time. 

If the resistance in the circuit increases, the time for discharging current in the circuit also increases.

A capacitor holds an electric charge like a bucket holds the water and takes a specified time to fill with current, and the resistance ascertains how fast the capacitor fills. 

  1. Use of Resistance for Diving Voltage

Dividing the voltage (the potential difference) works when some components are required to operate in a much lesser voltage than the supplied input voltage. Connecting the resistors in a series will aid in dropping the voltage across each resistor equally, thus, helping the appliances smoothly which works in those conditions.

FAQ (Frequently Asked Questions)

1. What are the different types of resistors and applications?

  1. Through-hole resistors

Through-hole resistors, accompanying the resistance, are rated according to the power they dissipate. They are the tiniest resistors with a value of 1/8W resistors, Here, ⅛ W means they can dissipate power 1/8 of a Watt or 125 mW. On the other end of the scale, you can find resistors in many appliances that dissipate a massive 100W.

  1. Variable resistors or potentiometer

As the name variable suggests, the value of the resistor can vary as per our requirements. 

You might have observed a big knob types variable resistors on radios to tune the stations or control the volumes. 

Also, there are small variable resistors, viz trimmers, are used to fine-tune/ calibrate an electronic circuit after the circuit-design is complete. 

  1. SMD Resistors

Surface mount device resistors are tiny in size and are designed to be soldered to the surface of PCBs.

2. Write uses of resistors.

  1. Current limit - A resistance works as a current limiting factor.

  2. Voltage dividers - We can make use of two resistors to divide a voltage by the ratio of their resistance values.

  3. Current shunts - 

Current shunts are low-value resistors that are used to measure currents without interrupting the circuit under test. They also have a high power rating. 

In this method, the current that is to be measured is allowed to pass through the resistor and the voltage drop across the resistor is measured. 

Therefore, once we know the voltage drop and the resistor value, we can use the ohms law, i.e., V=IR for calculating the value of the current.