Polarity and Continuity are terminologies that are associated with electrical and electronic components, and questions always arise whether resistors have polarity and continuity. This article shall delve deeper into these two concepts and see if resistors have polarity or continuity. 

What is polarity?

Polarity is a term that is used in many branches of science and technology such as electricity, magnetism, and chemistry. It is described as ; “a state or condition of an atom or molecule that exhibits opposite properties or powers in opposite parts or directions.” For example, a magnet is known for having North and South poles. Here magnetic polarity refers to the orientation of these poles in space. 

But, the polarity we are concerned about in this article pertains to electricity. So what exactly is electric polarity? 

Electric Polarity

Voltage can be defined as an Electromotive Force (EMF) between two points. When we are talking about these two points, we are looking at which point has more electrons than the other. The point that has more electrons is the Negative Pole, making the other point a Positive Pole.

Now when a conductor (such as wire) is used to close the path between the two poles, electrons flow from the negative pole to the positive pole (this flow of electrons is known as current). An example of this is a battery which has negative and positive terminals (or poles). Connecting a wire across the two terminals will cause electrons to flow from the negative terminal to the positive.

Components and polarity

So how does polarity relate to electrical and electronic components? They can be divided into two categories when it comes to polarity;

• Polarised or,
• Non-Polarized

Non-Polarised components do not have any polarity. These components can be placed in a circuit in any orientation without altering their functionality. 

Polarised components on the other hand have polarity. This means they have been constructed in a way where one of their terminals has more electrons than the other. They will have one negative and positive terminal. Therefore they will have to be placed in a circuit in the right orientation (their terminals must match the terminals of the voltage source). A common example of a polarised component is a battery. 

Do resistors have polarity?

No, resistors do not have polarity. They do not have positive or negative terminals which means that they can be placed in any orientation when connecting them up in a circuit. The main job of a resistor is to provide resistance to limit the flow of current. They are designed uniformly so that one terminal will not have more electrons than the other. The result being no matter what their orientation, they will still provide the same resistance.

A common analogy to better understand this is a road with bumps. Just like a resistor, the bumps on the road provide resistance when you drive past them. And just like a resistor, it doesn’t matter which way you are travelling, the bumps on the road are still going to provide the same resistance.

What is continuity?

Continuity is a term used in many aspects of life. It is defined as “the unbroken and consistent existence or operation of something over time.” When it comes to electricity the concept remains the same. Electric continuity refers to the presence of a continuous unbroken path for current to flow. 

Imagine we had a closed circuit with a battery source as seen below. 

The image below highlights two scenarios. Scenario A has a  wire that connects the positive terminal to the negative terminal without any physical breaks in it. Therefore it is said to have continuity as current can flow from the negative terminal to the positive terminal without interruption.

In Scenario B we see there is a physical break in the wire. In this instance current cannot flow from the negative terminal of the battery to the positive as there is no ‘continuous path’. Therefore the wire has no continuity.

Do resistors have continuity?

Yes, resistors do have continuity. Even though they might limit the flow of electrons (by providing a resistance), they still provide a continuous path for the electrons to through. 

Testing the continuity of a resistor using a multimeter   

Knowing if a wire or component has continuity or not is essential when it comes to circuit analysis. Wires and components are insulated to protect us from potential harm. But, if damage occurs it might be hard to detect it by just looking at it as the insulation might obstruct the damage. 

A multimeter is an electrical/electronic measurement tool used to measure things like voltage, current, resistance, etc. It also has the ability to test continuity. The multimeter has two probes that get  placed on two ends of wire for example. It then sends a current from one probe to the other (via the wire). If there is a break in the wire the multimeter will remain silent indicating no continuity. But, if the other probe receives the signal, this indicates that there is no break in the wire (hence it has continuity), and the multimeter will inform you with an audible beep. 

However, when testing the continuity of resistors, some issues arise. The multimeter’s continuity function works only below a certain threshold value of resistance. Anything above this threshold and the multimeter won’t be able to detect if there is continuity or not. So, even if a resistor with a high value of resistance has continuity, the multimeter might not pick it up.

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A capacitor is an electrical component that generates an electric field between its plates when a voltage is applied to its terminals. 

This electric field can then store electrical energy which can be used later. 

How much electrical energy a capacitor can store is determined by its Capacitance. 

The higher the capacitance, the more energy it can store and vice versa. 

But, should capacitors have continuity? Capacitors should not have continuity. However, when testing the capacitor using the continuity function of a multimeter you might get intermittent ‘beeping’ due to the capacitor charging and discharging. Note, this does not indicate that the capacitor has continuity. 

If there is a constant ‘beeping’ from the multimeter, this shows that there is continuity in the capacitor which means that it is faulty. 

Read on for more information why a capacitor should not have continuity. 

Brief look a the capacitor

Let’s take a brief look at the capacitor, which will give you a better understanding as to  why it should not have continuity. 

Capacitors are one of the three fundamental passive components used in electrical and electronic circuits (the other two being resistors and inductors).

As mentioned above, the capacitor has the ability to store energy in its electric field. 

They have many applications in a circuit with the most common being energy storage, voltage spike suppression and signal filtering. 

There are two types of capacitors; Polarised and Non-Polarised. 

A non-polarised capacitor is like a resistor and the orientation of its terminals does not matter when placing it in a circuit. 

Polarised capacitors however, have a positive and negative terminal, which means that they must be placed the right way round in a circuit. 

The basic construction of a capacitor

A capacitor is constructed using two metal plates which are separated by an insulating material known as the dielectric as seen in the diagram below.

The dielectric can be a range of insulating materials (inhibits the flow of current) which can include;

• Air
• Paper
• Glass
• Rubber
• Plastic 
• Ceramic

While the two metal plates are made from conductive materials (allows the flow of current) and can include metals such as;

• Aluminium
• Tantalum
• Silver
• Copper 

What is electrical continuity

Say you are crossing a bridge over a river.

If you can get from one side of the bridge to the other without falling into the river, the bridge’s path is said to be Continuous.

Now, imagine there is an earthquake which splits the bridge in half. 

You will not be able to cross the bridge safely as the path is no longer continuous

Electrical continuity pertains to the electrical and electronics world which states that for current to flow, it requires a complete path. 

In the above analogy the bridge would represent an electrical wire, and you crossing the bridge would represent the electrons flowing through that wire. 

Just like our analogy, if there is a break in the path the electrons will not be able to flow from one end of the wire to the other. 

What materials have electrical continuity

Electrical continuity exists in materials that are conductive. 

A conductive material is something that is effective at transferring or ‘conducting’ heat and electricity. 

This means electrons are loosely bound to their atoms within the material allowing them to move more freely.

Metals are very effective conductors  and are the main reason they are used in electrical and electronic circuits. 

Metals such as copper, silver, gold, tin, lead etc.

Insulators on the other hand are poor conductors. 

The electrons of the atoms within the material are held more tightly making it harder to transfer electrons (electricity and heat).

Continuity of the Multimeter

The multimeter is an electronic measuring instrument that is used daily for troubleshooting and analysing electrical and electronic circuits. 

Depending on the complexity of the multimeter, it can have the following functionalities;

• Read DC voltage
• Read AC voltage
• Test current
• Measure resistance
• Check diodes
• Transistor testing
• Continuity

The most basic of multimeters will have the ability to test continuity which is what we are concerned with. 

The continuity symbol on a multimeter is shown using a sound wave (like that emitting out of a speaker symbol), as it uses a beeping sound to indicate continuity. 

So how do you test continuity using a multimeter? 

Say you have a piece of wire (like in the picture below), and you want to test whether that piece of wire is continuous from one end to the other.

1. First set the multimeter to the continuity setting
2. Place one probe (negative or positive. The polarity does not matter), on one end of the wire (if the wire is insulated you will need to strip it first and place it on the conductive part of the wire).
3. Place the second probe on the other side of the probe.
4. If the wire has continuity the multimeter will produce a constant ‘beep’. 
5. If there is no continuity, there will be no beep

Note, if the material is somewhat conductive, there won’t be a beep but a resistance which will be displayed on the screen.  

Why a capacitor should not have continuity 

Now that we know the construction of a capacitor and how continuity works, we can take a look at why a capacitor should not have continuity.

The multimeter will only beep when a path is conductive and continuous. 

We saw that a capacitor consists of two metal plates separated by an insulating material, therefore a continuous, conductive path does not exist within the capacitor therefore it will not have continuity.

However, you might get intermittent beeping when first testing a capacitor.

This happens because the multimeter uses a small current to test resistance (and continuity is pretty much a really low resistance reading).

So when the probes are placed on the capacitor, the capacitor will start charging (due to the current) causing the beeping sound due to a small resistance present.

But, this does not mean that the capacitor has continuity. 

What happens if a capacitor does have continuity

If for some reason your multimeter has a constant beep when testing the continuity of a capacitor, this could indicate that the capacitor is faulty. 

If the dielectric inside the capacitor has ruptured causing the metal plates to touch, this will create a continuous path. 

But, you will not be able to use the capacitor anymore. 

How to protect capacitors from getting continuity

A faulty capacitor might have continuity as the two metals inside might be touching. 

But, this is not good as you will not be able to use the capacitor again.

There are couple reasons a capacitor might become faulty;

Static electricity 

If you handle the capacitors without an Antistatic Wrist Strap you run the risk of damaging it through static electricity. 

An Antistatic Wrist Strap reduces or removes electrostatic discharge which is the buildup of static electricity. 

Static electricity can damage electronic equipment like computer hard-drives and even ignite flammable liquids.

Exceeding maximum voltage and current ratings

Every capacitor has a maximum voltage and current rating.

These ratings let you know what maximum values of voltage and current it can handle before failure. 

So, be sure to check your capacitor ratings and stay below them.

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