Electromagnetic Spectrum-1

Authors Rajakani, Bartholomew Richard

Electromagnetic Spectrum

Electromagnetic Spectrum is a combination of different electromagnetic waves with different frequency. EM waves were order from lower frequency to higher frequency range. oh what are that?

" Radio waves, Microwaves, Infrared, Visible, UV, X Ray, Gamma Ray"

How to remember everything., it is easy dude.

Figure Credit: @chemistrywrites

Figure credit : Wikipedia

Radio waves

Radio waves are an higher wavelength electromagnetic wave. Clark Maxwell first predicted radio waves with his theory, which measured as unit in Hz.

you turn on a radio, the radio receives the radio waves in the air and converts them into an electrical signal, which is converted to sound waves, and the radio amplifier then boosts the sound waves so that you can hear the music.

Figure Credit : India times

radio wave is broadcast in different frequencies which can include FM radio waves that broadcast between 88 MHz and 108 MHz, and AM radio waves that broadcast between 550 kHz and 1600 kHz.

In modern days,

➡️Wi-fi uses radio waves that are routed through a wireless internet router using radio waves in frequencies between 2.4 and 5.8 GHz.

➡️text message being sent from a cell phone to another cell phone is a radio wave. The radio wave leaves the sender's cell phone and is sent to a tower that sends the wave to the recipient of the text. These are all unique radio waves being sent which makes it possible to reach the right person.

Microwaves

Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter; with frequencies between 300 MHz (1 m) and 300 GHz (1 mm)
The short wavelengths of microwaves allow omnidirectional antennas for portable devices to be made very small, from 1 to 20 centimeters long, so microwave frequencies are widely used for wireless devices such as cell phones, cordless phones, and wireless LANs (Wi-Fi) access for laptops, and Bluetooth earphones.
Antennas used include short whip antennas, rubber ducky antennas, sleeve dipoles, patch antennas, and increasingly the printed circuit inverted F antenna (PIFA) used in cell phones.

Microwave technology is extensively used for point-to-point telecommunications (i.e. non-broadcast uses). Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower frequencies because antenna size is inversely proportional to transmitted frequency. Microwaves are used in spacecraft communication, and much of the world's data, TV, and telephone communications are transmitted long distances by microwaves between ground stations and communications satellites. Microwaves are also employed in microwave ovens and in radar technology.

Infrared

Infrared (IR) radiation is characterized by wavelengths ranging from 0.750 -1000μm (750 - 1000000nm). Due to limitations on detector range, IR radiation is often divided into three smaller regions:
1️⃣ 0.750 - 3μm - Near infrared (NIR)
2️⃣ 3 - 30μm - Midwave -infrared (MWIR)
3️⃣30 - 1000μm – Far-infrared (FIR).
📢infrared radiation is in heat-sensitive thermal imaging cameras. These can be used to study human and animal body heat patterns, but more often, they are used as night-vision cameras.

Discovery of Infrared

With science you don’t always get what you want. But if you try sometimes, you get something even better. That’s what happened to William Herschel in 1800. While testing some light filters, Herschel used a prism to split sunlight into its component hues. Then he set up some thermometers. He knew that light falling on an object would warm it up, but he wanted to measure the effects of each color separate.

Then he noticed something strange: A thermometer at the end, beyond the red color—one that wasn't even in the light—also warmed up. What the heck? Of course the reason was that there was light hitting that thermometer, you just couldn't see it with human eyes. That was the discovery of what we now call infrared light.
Ok how we see the infrared rays?
Human eye is limited to visible light only beyond that cameras are used.

Stars are born inside thick clouds of dust. These clouds, or nebulae, are actually quite pretty.
If you see the image of ordinary Hubble telescope you observe there are stars inside those pillars of dust that Hubble can’t see.
visible light being given out by those stars is being obscured by the dust.
Then how to observe this?

So scientist using infrared reveals more structure to the dust clouds and hidden stars have now become apparent. And if Hubble can take an infrared image like this, imagine what JWST, which is 100x more powerful than Hubble, will do!

How infrared camera works?

All objects emit infrared energy, known as a heat signature. An infrared camera (also known as a thermal imager) detects and measures the infrared energy of objects. The camera converts that infrared data into an electronic image that shows the apparent surface temperature of the object being measured.

An infrared camera contains an optical system that focuses infrared energy onto a special detector chip (sensor array) that contains thousands of detector pixels arranged in a grid.

Each pixel in the sensor array reacts to the infrared energy focused on it and produces an electronic signal. The camera processor takes the signal from each pixel and applies a mathematical calculation to it to create a color map of the apparent temperature of the object. Each temperature value is assigned a different color.

The resulting matrix of colors is sent to memory and to the camera’s display as a temperature picture (thermal image) of that object.

Did you notice ever, when COVID was started spreading worldwide everywhere like shopping malls institution petrol pump railway station. Health care checkers were check our temperature with one device yes.. that is thermal camera which is used to measure body temperature 🌡️.how?🤔

Thermographic cameras can be broadly divided into two types: those with cooled infrared image detectors and those with uncooled detectors.

Cooled detectors are typically contained in a vacuum-sealed case or Dewar and cryogenically cooled. The cooling is necessary for the operation of the semiconductor materials used. Typical operating temperatures range from 4 K to just below room temperature, depending on the detector technology.

💫 In uncool detector, Non-contact temperature monitoring Camera it is used to immediately detects elevated skin temperature. Scans in compliance with social distance requirements

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