Chemistry · Structure Of Atom · NEET
From lowest energy to highest energy: Radio waves, Microwaves, Infrared (IR), Visible light, Ultraviolet (UV), X-rays, Gamma rays. As energy goes UP, wavelength goes DOWN. So this same list is also from longest wavelength to shortest wavelength. NEET often asks this order, so memorise it with the hook 'Raging Martians Invaded Venus Using X-ray Guns'.
High wavelength means LOW energy. Energy and wavelength are inversely related: E = hc/lambda. When lambda (wavelength) is large, E is small. That is why radio waves (very long wavelength) have the lowest energy and gamma rays (very short wavelength) have the highest energy. Students lose marks by assuming 'big wave = big energy' which is wrong.
An X-ray has far more energy. X-rays have a very short wavelength (about 10^-10 m) and radio waves have a very long wavelength (metres to kilometres). Since shorter wavelength = higher frequency = higher energy (E = h x nu), X-rays are much more energetic than radio waves. This is why X-rays can pass through skin but radio waves cannot harm you.
Yes, in vacuum every EM wave (radio, visible, gamma) travels at the same speed c = 3 x 10^8 m/s. What makes them different is their wavelength and frequency. Because c = nu x lambda is fixed, a short wavelength must have a high frequency. So the regions differ only in wavelength/frequency, not speed. This is a common NEET trap.
Violet has the highest energy and shortest wavelength (about 400 nm); red has the lowest energy and longest wavelength (about 750 nm). The visible order by increasing energy is: Red, Orange, Yellow, Green, Blue, Indigo, Violet (VIBGYOR reversed). Just past violet is UV (higher energy), and just past red is infrared (lower energy).
Visible light sits in the middle of the spectrum, between infrared (lower energy side) and ultraviolet (higher energy side). It is a very TINY part of the whole spectrum, only about 400 nm to 750 nm. Everything else (radio, micro, IR, UV, X-ray, gamma) is invisible to human eyes. NEET may ask which range is visible, so remember 400-750 nm.
A particular station of All India Radio, New Delhi, broadcasts on a frequency of 1368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is: [Speed of light, c = 3 x 10^8 m s^-1]
Which of the following series of transitions in the spectrum of the hydrogen atom falls in the visible region?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It can be written either way, but the standard NEET order Radio to Gamma is by DECREASING wavelength (and INCREASING energy/frequency). Radio has the longest wavelength; gamma has the shortest.
Yes. In vacuum, every EM wave travels at the speed of light, c = 3 x 10^8 m/s, no matter its wavelength. They differ only in wavelength and frequency, not speed.
Gamma rays have the highest frequency and therefore the highest energy and shortest wavelength. Radio waves have the lowest frequency and energy.
Use 'Raging Martians Invaded Venus Using X-ray Guns' for Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma. This runs from lowest energy to highest energy.
NEET Structure of Atom questions test which region a given wavelength or frequency belongs to (like radio waves in the 2021 PYQ) and where hydrogen spectral series fall. Getting the wavelength-energy relationship right saves easy marks.
