Light bulbs are one of the greatest inventions. They provide homes with light and led to other technological advancements. However, are light bulbs resistors?
Light bulbs are not resistors, but they behave like resistors. Resistors limit the flow of electrons and change the energy to a different form. This is similar to how electricity travels through a light bulb and becomes light and heat. The filament in light bulbs acts as a resistor.
To understand light bulbs and their role as resistors, you must understand the definition and the importance of resistors, as well as how to find the resistance of certain light bulbs.
What is a Resistor?
A resistor is anything that electricity cannot travel through easily.
It is a passive electrical component that creates resistance in the flow of electric current. At least one type of resistor can be found in almost all electrical and electronic circuits.
In electronic circuits, resistors are used to reduce current flow.
- Resistors allow electronics to be used safely and effectively because they protect products from an overflow of electricity. Laptop chargers, temperature controls, and heating appliances have resistors.
Resistors are typically made of copper or carbon. This makes it difficult for electrical charges to flow through a circuit. Limiting electric charges limits shocks and other potential malfunctions.
Resistors also protect against voltage spikes. Appliances that are sensitive to a high electrical current will be damaged if there is no resistor. The resistor controls the flow of the electric current.
A light bulb must act as a resistor.
By doing so, the light bulb is safe to use and safe to have in your home. A resistor keeps the light bulb from getting too hot.
If a light bulb gets too hot, it becomes a fire hazard.
A hot light bulb is also more prone to breaking than a cold light bulb. Resistance also controls the levels of brightness. You can buy light bulbs with higher or lower levels of resistance depending on how bright and warm you want your lights to be.
Why Aren’t Light Bulbs Resistors?
Light bulbs function like a resistor, but fundamentally they are different.
The filament in a light bulb is the part of the light bulb that functions as a resistor. The filament is a conducting wire or thread with a high melting point.
That wire is heated by an electric current. As electricity flows through the filament, that energy is transformed into heat and light.
A resistor transforms electrons as those electrons pass through the resistor. This is similar to how the filament transforms electricity into heat.
However, light bulbs are not true resistors.
Lightbulbs are not true resistors because they do not have constant resistance. They gain resistance as they heat up.
When a light bulb is turned on, it has a low amount of resistance. As the light bulb heats up, the resistance increases.
Once it heats up enough, the resistance stabilizes. Because the resistance is not constant and relies on heat to become resistant, it can not be considered a true resistor. It does, however, act very similar to a resistor.
How do you Find the Resistance of a Light Bulb?
You find the resistance of a light bulb by using Ohm’s Law of Resistance.
Ohm’s Law states that the voltage or potential difference between two points is directly proportional to the current or electricity passing through the resistance, and it is directly proportional to the resistance of the circuit. The formula for Ohm’s Law is V=IR or Voltage= Current x Resistance.
To find the resistance of a light bulb you divide the voltage (V) of that current light bulb by the current (I).
Voltage is the potential for energy to move. The most common voltage for a light bulb is 120 volts. You can look at the data imprinted on the side of most light bulbs. Inscribed on the light bulb, should be the voltage of the bulb.
Current is the rate at which electricity flows through the unit. The current is measured in Amps (A). You can find the current of a light bulb by dividing the power output of a circuit by the voltage of that circuit.
Once you have the current and the voltage you can then use Ohm’s formula to find the resistance.
This law is one of the most basic laws of electricity. It is used to help calculate the power, efficiency, voltage, and resistance of an electrical circuit. Ohm’s Law of Resistance was revolutionary. It allows for calculations that can make electricity safer.
Having lights with extremely high levels of resistance can be dangerous. Ohm’s Law allows for the levels of resistance and voltage in light bulbs and other electrical devices to be monitored.
What is the Resistance of a 20W 120v Light Bulb
The resistance of a 20w 120 v light bulb is 360 ohms. A light bulb with only 20 Watts will have average brightness. A significantly bright bulb would have 100 Watts.
A light bulb with 83 ohms would have the brightness of a bulb found in the average home. This light bulb also would not get very hot. Some light bulbs tend to get very hot if they are left on for long periods of time.
This is because they have high levels of resistance. The higher the resistance, the hotter the light bulb will be.
This light bulb is relatively safer than higher resistance light bulbs because it will not get hot and burn you.
What is the Resistance of a 12V 10W Light Bulb
The resistance of a 12 V 10 W light bulb will be very low. This light bulb will typically have a resistance of 85 ohms and doesn’t produce bright light. Lights with this type of resistance tend to be small lights.
You would find these types of light in flashlights or smaller devices.
Low resistance means the light will not produce a large amount of warmth or light. These lights also tend to be less expensive and will not last as long as a light bulb with a higher resistance.