LED stands for "light-emitting diode." When electricity is conducted through an LED bulb, the electrical energy forces excited electrons within semiconductor material to release photons. These released photons are what makes LEDs so efficient - because they don't waste heat in the process of generating light as incandescent bulbs do, and they last much longer than fluorescent lights.
How do LED bulbs work?
The semiconductor material is shaped into a long, thin strip about the size and shape of a typical grain of uncooked rice. A "carrier" current runs through this strip, exciting some electrons and leaving others unaffected. Once the excited electrons lose their energy, they release photons as light so that all those passing by see exactly the same amount of light from any given LED bulb.
Why should you know the polarity of the bulb?
Understanding the polarity of LED bulbs is important because it will affect how they perform in terms of color. To put it simply, an LED bulb has to be connected with its positive end touching a terminal's positive node and negative end touching the negative node for maximum performance.
If this isn't done, the light coming from the bulbs won't be as bright or colorful. Knowing a bulb`s polarity will help you to connect the bulb with ease.
What is polarity?
Polarity is a characteristic of a circuit in which there are two distinct voltage polarities, one for each direction that current can flow. When electricity flows from positive to negative, we call this direct current or DC. When it goes from negative to positive, we call this alternating current or AC.
Also, polarity in DC circuits is usually denoted by either + and - signs showing where you should connect the power supply wires. In AC circuits it's more complicated because the direction of electrons changes periodically with 60 times per second in the US and 50 times per second in Europe.
Plus
Minus
Do LED bulbs have polarity?
Yes, all LED bulbs have polarity. That means that if you wire them incorrectly, they won't work at all.
A LED bulb consists of at least two parts: the positive and negative power contacts, and the semiconductor diode that actually produces light. Each part is essential for making an LED work. The positive power contact injects electrons into the semiconductor material, which causes it to release photons. The negative contact collects excess electrons from this process.
Inside every LED bulb are "p-type" semiconductors (positive) and "n-type" semiconductors (negative). When electricity flows through a p-type semiconductor, excited electrons within the atoms are forced to leave their orbits around those atoms' nuclei - leaving behind positively charged holes where those excited electrons used to be. Electricity then flows through the n-type semiconductor similarly to how it flows through a p-type, but excess electrons are collected instead of being forced out.
LED diode polarity
LED diode polarity is extremely important to keep in mind when working with these tiny little lights. If you connect your LED up backward, it simply will not light up. The reason for this is that the electrical current can only flow in one direction through an LED, and if you connect it up backward, the current cannot flow at all.
This is why it is important to note the polarity of an LED when connecting it up to a power source. The longer lead on the LED is always the positive (+) lead, and the shorter lead is always the negative (-) lead. You can remember this by thinking of the long lead as the "head" of the LED and the short lead as the "tail."
If you connect your LED up with the wrong polarity, don't worry, you haven't ruined it. You can simply flip the LED around and it will work just fine.
Plus
Minus
How does polarity work?
Most LED bulbs have metal legs that indicate which terminal should be connected to the ground or power source. If your LEDs don't light up, try switching the polarity.
Be aware of how you hook up your power supply because this could change how an LED bulb works. Reverse voltages may not destroy an LED, but they can cause flicker and affect its lifespan. These devices are sensitive to changes in voltage, so it's important to find a constant source of power (e.g., batteries) if possible.
Polarity is very important for LED lights because these devices will not work with electricity flowing through them backward. Thus, both poles (positive and negative) should be correctly connected to ensure forward current flow. Otherwise, your LED will not light up.
Having the correct polarity allows an LED bulb to function while reverse polarity will cancel out the electrical charge that makes an LED work. Thus, it's important to make sure you are correctly hooking up these devices.
How to tell if a LED bulb is polarized?
There are three distinct ways that you can visually identify whether or not an LED bulb is polarized. One of which is the horizontal orientation on the packaging - if it's horizontal, then it isn't polarized. The second way is by identifying the '+' and '-' on either side of the LED bulbs where one of them has a visible flat edge on one side. This visible flat edge will have to be touching one of the terminals for correct polarity.
The third way is by checking out what terminals your lightbulbs have - if they have 4 pins in a square formation, then they're polarized these pins represent each terminal that they need to be connected with in order to function properly.
Why does the orientation of an LED bulb matter?
LED bulbs are polarized - this means they have to be connected with their positive end touching a terminal's positive node and negative end touching the negative node for maximum performance. If the polarity is reversed, then that will cause the light coming from it not to be as bright or colorful.
If you want your LED bulbs to perform at their best, then you'll have to make sure that it's connected correctly according to which terminals they have whether horizontal or otherwise. If your LED bulb has 4 pins in a square formation rather than horizontal, then it too will have correct polarity by connecting its '+' pin touching one of the terminal's '+' nodes and '-' pin touching one of the terminal's '-' nodes.
Hence, it is hard to be incorrect when identifying the polarity of LED bulbs. The only way you can be incorrect in determining its polarity is either if your bulb has four pins rather than two, or if the horizontal orientation on the packaging says otherwise.
How can you know where are positive or negative LED bulb legs?
The key to correctly wiring an LED bulb is knowing which contact (the positive or negative one) should be connected where (to the positive or negative power source). If you wire an LED incorrectly, no electricity will flow through it. The light won't come on at all because the electrical charge required to make the bulb work cannot complete its circuit!
If you wire your LED bulb with polarity, however, it should turn on. Wiring your LED right depends on whether it has clear (transparent) or frosted (opaque) glass. With clear glass, the positive and negative contacts are labeled on the base of the bulb with a plus-shaped half circle and a minus-shaped half circle.
Frosted glass bulbs won't have these labels, but you can determine which is which by looking for shorter metal legs , which represent the negative contact. If both positive and negative contacts have short metal legs, it's probably a rear-facing light (that is not meant to be installed facing up), so it doesn't matter if they're hooked up backward because no one will see the back when it's installed.
To identify where are positive or negative legs of any LED bulb you have to look for two short metal pads - one positive and the other negative. The longer leg would be positive and the shorter one - negative.
The base of a clear bulb has two small half-circles, one black, and the other white. The negative (shorter) leg is usually on the left; the positive (longer) leg goes to the right. This information should be clearly printed on the base of LED bulbs. If it isn't there or you can't make sense of it, you can use a multimeter to test for power and ground.
How do you wire LED bulbs with polarity correctly?
Many types of LED light bulbs are labeled with either a plus or minus sign. If yours isn't, try to find out which contact is which by looking at the shorter metal legs on your light bulb. The contact with the shorter leg is typically the negative one. If both contacts have relatively short legs, it's usually not meant to be installed facing up (e.g., in an exterior lamp or fixture), so it doesn't matter if they're hooked up backward because no one will see the back when it's installed.
The positive power supply should go through the positive contact inside an LED bulb, and the negative power supply should go through the negative contact. Ensure that your positive power source (usually this is an AC wall adapter) has enough voltage to light up the LED bulb.
When wiring in series, make sure you do not exceed the total current of all connected LEDs. If you are using a 12V DC power source, make sure it does not exceed 18W per LED bulb for 120V/240V bulbs or 9W per LED bulb for low-voltage bulbs.
Connect positive (+) wire to positive contact inside LED lamp and connect negative (-) wire to negative contact - that's how you correctly wire any LED bulb with polarity.
How does polarity affect LED power consumption?
It's important to note that connecting an LED bulb incorrectly won't damage anything or cause any safety issues - as long as the LED still works. If you connect an LED bulb with reverse polarity, however, it won't light up. This is because connecting the positive and negative power supply in reverse will cancel out the electrical charge that makes an LED work!
If your LED bulbs turn on with incorrect wiring (and it's a rear-facing fixture), leave them alone and don't touch anything - doing so could cause a short circuit or shock
LED light bulbs usually have internal circuitry that turns the alternating current into the direct current required to make LEDs function properly. If one of these circuits fails, you can get either no electricity or too much electricity flowing through your device. No electricity means no lights, but too much can cause damage to your devices.
If you do get electricity flowing where it shouldn't be, unplug the device immediately to prevent anything bad from happening. Disconnect or cut the power supply coming into your LED bulbs and don't touch anything until you check for damaged wires or circuits. If everything is fine, try switching out the bulbs.
A LED light bulb can work if connected with polarity opposite to forward operating voltage direction. However, there are limits of acceptable polarity reversal in order not to damage an LED bulb negatively.
Summary
Polarity is a characteristic of a circuit in which there are two distinct voltage polarities, one for each direction current can flow through them.. If you connect an LED bulb with incorrect wiring (and it's a rear-facing fixture), leave them alone and don't touch anything - doing so could cause a short circuit or shock.
This is because connecting the positive and negative power supply in reverse will cancel out the electrical charge that makes an LED work!
Polarity affects LED power consumption because if you connect an LED bulb with reverse polarity, it won't light up. This is because connecting the positive and negative power supply in reverse will cancel out the electrical charge that makes an LED work!
When wiring in series, make sure you do not exceed the total current of all connected LEDs. If you are using a 12V DC power source, make sure it does not exceed 18W per LED bulb for 120V/240V bulbs or 9W per LED bulb for low-voltage bulbs.