Question: In an electromagnetic spectrum, identify which of the following lists are ordered from the longest w...

Question

In an electromagnetic spectrum, identify which of the following lists are ordered from the longest wavelength to shortest wavelength?
A. X ray, ultraviolet, visible light
B. Visible light, ultraviolet, X-ray
C. Ultraviolet, X-ray, visible light
D. Ultraviolet, visible light, X-ray
E. X-ray, visible light, ultraviolet.

Answer 1

Solution

In order to answer this question, one must be aware of the value of wavelength of these given rays. The Energy of the x-ray is greatest among the following and the energy of visible light is lowest. Energy is inversely proportional to wavelength of rays.

Complete answer:
We must know either the order of the wavelengths of the given rays or the energies of the given rays in order to answer the question. The wavelength of the following rays are as follows:
X-rays: X-rays are high-frequency rays, their frequency is very high. This implies that they have high penetration power and electromagnetic radiation. Their wavelength is in the range of $0.01nm - 10nm$ .
Ultraviolet rays: Ultraviolet rays are the one through which the Ozone protects us. Basically, the wavelength of the ultraviolet rays is in the range of $100nm - 400nm$ .
Visible light: Humans can see objects only when it reflects light in visible wavelength range. The visible light consists of seven different colors. Their wavelength is in the range $380nm - 700nm$ .
From the above values, the decreasing order of wavelength can be easily found out.
The decreasing order of wavelength is: Visible light, ultraviolet, X-ray

So, the correct answer is “Option B”.

Additional Information:
The seven colors of visible light in increasing order of their wavelength is: Red, Orange, Yellow, Green, Blue, Indigo and Violet. Don’t confuse it with VIBGYOR mnemonic. Order of wavelength is the reverse of VIBGYOR.

Note:
Remember that the decreasing order of energies of these rays will be exactly opposite.They have high penetration power and electromagnetic radiation .Also, remember that the question asks for decreasing order and not increasing order. Remember the wavelength range of visible light.