In the vast range of electromagnetic waves red light as well as infrared lights play distinct and important functions in our lives. While red light is within the limits that our eye sees, infrared is obscure to our perception as it is beyond all visible wavelengths.
The distinct properties of infrared light affect their application, ranging from the simple nature of traffic signals to the complexity of the thermal images. Read this article to discover the fundamental distinctions between the two neighboring spectral regions.
What is Red Light?
Red light is a type of electromagnetic radiation that is part of the visible spectrum. It is distinguished by wavelengths ranging from 620-750 nanometers (nm). This is by far the longest wavelength that is visible to the human eye and has a distinct red color.
The spectrum, located close to the visible light spectrum has a lower energy level than other colors visible to the eye, such as green or blue. The main examples of sources of red light are the sun and lasers, light bulbs, and a variety of electronic displays. Its characteristics make it a key element in a variety of applications such as traffic signals to photographic filters.
What is Infrared?
Infrared (IR) is electromagnetic radiation with wavelengths that are longer than visible red light, but less than microwaves. Infrared wavelengths usually vary from 500 nanometers (nm) all the way to one millimeter (mm). Contrary to visible light, the infrared spectrum isn’t visible to our eyes, rendering it unnoticeable.
It is perceived as heat since numerous objects emit infrared light as thermal radiation. The word “infrared” translates to “below red” which indicates it is located just above the red light of the spectrum of electromagnetic radiation. Infrared has many applications such as remote controls thermal imaging, communications, heaters, and telecommunications.
Comparison Table Red Light and Infrared
Certainly! Here’s a streamlined comparison table focusing directly on red light and infrared:
| Feature | Red Light | Infrared |
|---|---|---|
| Wavelength Range | 620-750 nm | 750 nm to 1 mm |
| Visibility | Visible | Invisible |
| Energy Level | Lower | Higher |
| Perception | Seen as a red color | Felt as heat |
| Typical Sources | Traffic lights, LEDs, lasers | Remote controls, human body, heaters |
| Applications | Signaling, photography, visual alerts | Thermal imaging, telecommunications, heating |
| Safety Concerns | Eye strain from intense sources | Skin burns from high intensities, eye damage from certain IR lasers |
This concise table offers a clear and direct contrast between red light and infrared in various aspects.
Visible spectrum and the position
The spectrum of visible light, commonly referred to as the light spectrum, is the spectrum in electromagnetic waves that is observed in the eyes of a human. It’s only a tiny portion of the whole electromagnetic spectrum.
Here’s a breakdown of the visible spectrum, and the location of the colors in it:
Visible Spectrum:
- Wavelength The range of HTML0 is About 350 numeric units (nanometers) up to 775 nm.
Color Position (from the shortest to the longest wavelength):
- Violet: 380-450 nm
- Blue: 450-495 nm
- Green: 495-570 nm
- Yellow: 570-590 nm
- Orange: 590-620 nm
- Red: 620-750 nm
When we shift from red to violet, the wavelength is increased and the energy is reduced. This is the reason the blue light (shorter wavelength, more energy) may be more dangerous to the eye than the blue light (longer wavelength, less amount of energy) in certain circumstances.
Prior to you see the spectrum in visible (at lower ranges) are the UV (UV) spectrum. Then right following (at higher distances) is the spectrum of infra-red (IR) spectrum.
Applications of red light in everyday life
Red light is used in a range of uses in our everyday life due to its unique properties and transparency.
Here are a few common applications of red light in our everyday lives:
- Traffic Signals: A red light at traffic signals generally indicates “stop” or “halt” to regulate pedestrian and vehicular traffic.
- Emergency Vehicles: Flashing red lights in fire trucks, ambulances, and other emergency vehicles indicate the need for the importance and urgency of the roads.
- Brake lights: Cars utilize red light bulbs to signal a slowing or stopping.
- Rear bicycle lights: Bicycles typically feature red lights in the rear for nighttime visibility. They signal their presence to motorists who are behind them.
- Photography: Red light is utilized in darkrooms as they do not affect certain photosensitive materials, which allows photographers to use film without damaging it.
- Astronomy: The red flashlights can be employed by astronomers as well as stargazers since they don’t hinder night vision in any way and allow the eyes to remain adapted to the darkness.
- Alarm Clocks A few alarm clocks utilize LED displays in red since red light is less disruptive for sleep than other shades.
- Entertainment:
- Movie Exit Signs: Signs with exit lights that glow red help moviegoers who are in dark theaters.
- Stage shows and concerts: Red stage lighting creates specific moods and themes throughout performances.
- Therapie: Therapy with Red Light Therapy (or photobiomodulation) is used for many purposes of therapy, including treatment of wounds, skin care, and pain management.
- Power Indicates: Many electronic devices and appliances are equipped with red LEDs that indicate the power level or specific modes of operation.
- Remote Controllers: The light emanating from remote controls for TVs and other electronic gadgets is usually infrared (and therefore invisibly) however, some may feature an apparent red LED that indicates the signal’s transmission.
- Gaming: Gaming and PC peripherals such as keyboards and mice, are equipped with red backlighting, or LEDs to enhance the look of the device.
- Security and Warn Signs: The red light is commonly utilized as a safety signal and indicator due to its excellent visibility and is associated with a sense of danger or alertness.
There are a variety of instances of red light usage in daily life. Its visibility, particularly when it is dark and its widespread relationship with caution or significance is a crucial tool in many scenarios.
Location of infrared radiation on the electromagnetic spectrum
The electromagnetic spectrum covers an extensive spectrum of electromagnetic radiation. It ranges from gamma radiations that are extremely short to extremely lengthy radio waves. Every kind of radiation within the spectrum is identified by a specific frequency or wavelength.
The Infrared spectrum (IR) is situated between the visible light spectrum and the microwave light in the spectrum of electromagnetic radiation. Here’s a brief overview of its location:
Electromagnetic Spectrum (from shortest to the broadest length):
- Gamma Rays Extremely low wavelengths and high energy.
- X-rays very: shorter wavelengths, but slightly more than gamma radiations.
- Ultraviolet (UV) Radiation: Just before the visible spectrum, which is responsible for sunburns, and is dangerous in large amounts.
- Visible Light This is the part of the spectrum a human eye is able to detect. It spans between violet (shortest wavelength) to red (longest wavelength).
- Infrared Radiation (IR): It immediately follows the visible spectrum. While it’s inaccessible to the naked eye, however, we are able to feel it in the form of heat. It is further classified into:
- Near-Infrared (NIR): Closest to the visible spectrum, commonly employed in electronic devices such as remote controls.
- Mid-Infrared (MIR): Typically detected as heat.
- Far-infrared (FIR): Also detected as heat, it is utilized in a variety of therapeutic applications.
- Microwaves: More long-wavelengths and longer wavelengths than IR that are used in microwave ovens as well as certain technologies for communication.
- Radio Waves: One of the most long wavelengths that are used for all wireless communications. This includes AM and FM radios television, as well as cell phones.
So, infrared radiation sits just beyond the red end of the visible light spectrum, bridging the gap between visible light and microwaves. Its position gives it unique properties, allowing it to be used for everything from TV remote controls to thermal imaging.
How infrared radiation interacts with objects
Infrared (IR) radiation interacts with objects through the induction of motions and vibrations within molecules, which can cause a variety of effects, including heating.
These points describe the ways infrared radiation interacts with objects:
- Absorption and Emission:
- Absorption: If IR radiation hits an object, the molecules inside the object will take in the radiation. The absorption increases the energy of the object’s interior which is often manifested as a rise in temperature.
- Emission: Objects at a temperature higher than Absolute Zero produce IR radiation. This is the reason why thermal cameras are able to see the “heat signatures” of objects and living beings. The warmer an object is emit greater the amount of IR radiating radiation that it produces.
- Vibrational and Rotational Excitations:
- Molecules exhibit a variety of vibrational as well as rotational modes. IR radiation may trigger these modes, which causes molecules to spin or vibrate faster. Different bonds and molecules absorb IR radiation in specific wavelengths, and this forms the foundation for infrared spectroscopy, an instrument that is used to determine chemical compounds.
- Thermoconduction: In the event that IR radiation is absorbed by an object and its energy grows, the energy may be transmitted to nearby areas or particles, thereby expanding the warming effect.
- Reflection, Transmission, and Refraction:
- Reflection: Similar to sunlight, IR radiation can be reflected off surfaces. Metallic surfaces with shiny surfaces, for instance, reflect the IR.
- Transmission: A few materials let IR radiation be absorbed by them, for instance, some types of plastic or glass. This transmission could be frequency-dependent and only certain IR wavelengths are able to pass through.
- Refraction: The IR spectrum can bend when it passes from one medium to the next with a different density like visible light refracted inside prisms.
- selective absorption All objects don’t absorb IR radiation in the same way. Materials have emissivities that differ and determine the efficiency with which the absorber and emission of IR radiation. Dark matte surfaces usually have high emissivities and are excellent absorbers. On the other hand, shiny metallic surfaces have lower emissivities, and are not good absorbers, but are excellent reflectors.
- Thermal Expansion: As an object absorbs IR radiation and heats up, it can undergo thermal expansion–increasing in size due to the added energy.
- Heating effect: A variety of practical uses like IR saunas or heaters employ the heating effect of IR radiation. The devices release IR radiation that delivers warmth directly to the objects or individuals within their reach.
- Live Tissue Interaction: Infrared radiation is able to be absorbed just beneath the skin’s surface for animals and humans, increasing the flow of blood and aiding in healing in certain situations. This concept is employed for infrared treatment.
Understanding how infrared radiation interacts with objects is essential for a variety of applications, ranging from scientific research employing infrared spectroscopy, to everyday applications like cooking using an infrared grill or the infrared thermometer.
Health and safety considerations with infrared radiation
Although Infrared radiation (IR) is used extensively in a variety of applications there are safety and health concerns to consider:
- Skin Burns:
- Exposure to high-intensity IR radiation may result in skin burns, like burns from an object that is hot.
- devices that emit intense IR radiation, for example, certain industrial equipment or heaters can pose a danger when people are too close for a prolonged time.
- Eye Damage:
- The eyes are especially vulnerable in response to IR radiation. Although our eyes respond naturally to shut or blink when exposed to intense visible light they don’t have a similar reflex to IR because it’s not visible.
- Direct or prolonged exposure to high-intensity IR particularly from lasers and other powerful sources, could cause retinal burns and cataracts.
- Heat Stress:
- In areas that are exposed to excessive IR radiation, for instance, specific industrial settings, there’s an increased risk of experiencing heat stress. The condition develops because the body can’t disperse the heat efficiently and causes symptoms such as extreme sweating and dizziness and, in extreme instances even heatstroke.
- Infrared Saunas:
- Infrared saunas make use of IR heaters to heat our bodies directly. Although they’re generally considered to be safe and offer positive therapeutic effects, it’s vital to:
- Keep hydrated.
- Limit sessions around 15-30 minutes.
- Be aware if you suffer from particular medical issues Always consult your doctor before taking any sauna that uses infrared radiation.
- Infrared saunas make use of IR heaters to heat our bodies directly. Although they’re generally considered to be safe and offer positive therapeutic effects, it’s vital to:
- Fire Hazard:
- Certain devices emitting IR radiation could become extremely hot, and pose a hazard of fire should they come in contact with any flammable material.
- False Sense of Security:
- Because IR is invisible There’s a chance of being tempted to believe that an item isn’t emitting radiation even when it’s. Always make use of indicators or sensors to verify whether an IR-emitting device is operating.
- Infrared Lasers:
- IR lasers, specifically those with high power can pose serious risks. In the absence of proper safety equipment, it is possible to suffer eye injury. Infrared laser beams can be invisible and can make accidental exposure more likely should safety precautions not be properly in place.
- Protective Gear:
- In areas where there is an increased risk of IR exposure, like near certain industrial equipment or working using IR lasers, be sure to wear protective equipment. This could include IR-resistant goggles masks, face shields, or clothes.
Although infrared radiation is not ionizing (meaning it does not have the energy to ionize atoms and molecules, and thus harm DNA in the same way that Gamma rays or X-rays do) however, it does carry thermal energy.
The primary dangers of IR exposure involve burns and thermal injuries. An understanding of the equipment respect for the equipment and following safety guidelines will reduce the risk.
Applications of red light in everyday life
Red light is used in many ways throughout the day due to its unique properties and visibility.
Here are a few common applications of red light:
- Traffic Signals: Traffic signals with red signal signals all over the world for pedestrians and cars to slow down.
- Emergency vehicles: Emergency vehicles like ambulances, fire engines, police cars, and ambulances utilize flashing red lights to indicate emergencies and demand access to the road.
- Red Lights for Brake: Automobiles and many other vehicles rely on brake lights that are red to signal that they are braking for those in the rear.
- Night Vision: Certain headlamps, flashlights, and other lights come with an option for red light, which can help maintain night vision since the red light has less chance of being able to dilate the pupils nearly as significantly as blue or white light.
- Photography Darkrooms: Red safety lights are commonly utilized in darkrooms, in which photographic film is created because a variety of black and white photographic paper is insensitive to red lights, which prevents the paper from accidentally being exposed.
- Alarm Clocks: The red LED option is commonly used for digital clock displays, specifically in clocks for bedrooms since the red light is more peaceful for sleep as than white or blue light.
- Entertainment:
- Theatre Lighting: Lights in red are used in theatre, concerts as well and other events to create dramatic or moody effects.
- Decor: The red LED strip bulbs and lights are used for decoration during celebrations or for general decoration in the home.
- The Red Light Therapy: A therapeutic practice that utilizes low-level red wavelengths to treat skin problems like wrinkles, scars, and chronic wounds as well as other ailments.
- Safety and Indicators:
- Aviation: Red lights are located on the left side of the edge of the aircraft’s wings to help pilots keep their eyes on the road in night flight and to prevent collisions.
- Boating: The red lights show the side of the port (left) side of a vessel.
- Exit signs: The majority of exit signposts for emergency evacuation are illuminated in red so that they can be easily visible and easily recognized.
- Gaming: Gaming-related peripherals such as mice and keyboards could include red backlighting, or LED elements to enhance aesthetic appeal.
- Astronomy: The red LEDs in flashlights can be utilized by astronomers to study star maps and adjust telescopes, without affecting the night vision of their telescopes.
- Status and Power Indicates: Many electronic devices such as computers, televisions, and other gadgets feature red LEDs that indicate the status of power off or certain operating modes.
- Remote Controllers: Although the LED that transmits signals from remote controls is usually infrared (invisible) some remotes feature visible red LEDs that light up when the button is pressed to signal that a signal has been transmitted.
There are a myriad of the many ways we can use red light in our everyday lives. Its visibility, particularly when it is dark and its general connection with importance, alertness, or prudence make it a valuable tool in many different contexts.
Wavelength and frequency variations
The frequency and wavelength are two key parameters that define electromagnetic waves, such as the visible spectrum, radio waves, and X-rays. The relation between frequency and wavelength is inversely proportional. As one grows, the other diminishes.
The relationship can be described using the equation:
=xc=lxf
Where:
- C is the speed of light in the vacuum (approximately 3x1083x108 meters per second).
- L (lambda) represents the wavelength.
- The rate at which the waves propagate.
Let’s now look at the differences in wavelength and frequency:
- Wavelength (l):
- It’s how far between two peaks (or the troughs) of the wave.
- It is usually determined by meters (m) or equivalents such as nanometers (nm) for visible light or millimeters (cm) for microwaves, etc.
- The longer wavelengths correspond to radio waves, whereas shorter wavelengths correspond to gamma radiation.
- Frequency (f):
- It’s the number of cycles of waves that pass through one point at a particular time of time.
- It is typically determined by Hertz (Hz) in which one Hertz represents one cycle every second.
- The higher frequencies correspond to the gamma radiation, whereas lower frequencies are radio waves.
Examples of Wavelength and Frequency Variations in the Electromagnetic Spectrum:
- Radio Waves:
- Wavelength: >1 meter (can range from several miles in some radio waves)
- Frequency: 3 kHz to 300 GHz
- Microwaves:
- Wavelength: 1 millimeter to 1 meter
- Frequency: 300 MHz to 300 GHz
- Infrared:
- Wavelength: 700 nm to 1 mm
- Frequency: 4x10144x1014 to 300 GHz
- Visible Light:
- Wavelength: 400 nm (violet) to 700 nm (red)
- Frequency: 4.3×10144.3×1014 Hz (red) to 7.5×10147.5×1014 Hz (violet)
- Ultraviolet:
- Wavelength: 10 nm to 400 nm
- Frequency: 7.5×10147.5×1014 Hz to 3x10163x1016 Hz
- X-rays:
- Wavelength: 0.01 nm to 10 nm
- Frequency: 3x10163x1016 Hz to 3x10193x1019 Hz
- Gamma Rays:
- Wavelength: < 0.01 nm
- Frequency: > 3x10193x1019 Hz
Remember that, as the wavelength decreases (moving between radio waves and gamma radiations) the frequency becomes higher. However, as the wavelength increases (moving from gamma radiations to radio waves) the frequency becomes lower.
Conclusion
Frequency and wavelength are two fundamental parameters that define electromagnetic waves. They exhibit an inversely proportional relationship. This means that when one is increased in frequency, the other will decrease.
They range across the spectrum from radio waves that are long, to short Gamma Rays, the variations in frequency and wavelength throughout the spectrum of electromagnetic waves allow numerous effects and phenomena that we see every day including radio broadcasts and medical imaging.
Understanding their interaction is vital to harness the power of electromagnetic waves across a variety of technical and scientific domains.
