Question

Which wavelength of sun is used finally as electric energy?
A) Radio waves
B) Infrared waves
C) Visible light
D) Microwaves

Answer 1

Hint: In order to solve this question you have to know all the concepts related to waves, their wavelength and their properties. Also, you know their applications. Always remember that the heating property of infrared waves is used in solar heaters and solar cells.

Complete step by step solution:
Radio waves are a type of electromagnetic radiation with a frequency higher than $300GHz$. These waves can be transmitted easily through the air. These waves do not cause damage if absorbed by the human body, and they can also be reflected to change its direction. So, these waves are used for communication.

Infrared waves are a type of electromagnetic radiation with wavelength between $70nm$ and $1mm$ . These waves are just beyond our eyes to detect. Infrared waves or heat waves are used for heating thermocouples to produce electricity. The heating property of infrared waves is used in solar heaters and solar cells.

Visible light is also a type of electromagnetic radiation that the human eye can see, that range of waves is called visible light. These waves have wavelengths between $380 - 700nm$. This wave is very important to the human eye, without it our eyes aren’t able to see.

Microwave is also a type of electromagnetic radiation with a wavelength in the range of $1m - 1mm$. These waves are widely used in point-to-point communication links, spacecraft communication, wireless networks, cancer treatment, radar, etc.

Therefore, the correct answer is option (B), infrared waves.

Note: Infrared also known as IR light is also used by electric heaters, optical fibers, thermal imaging cameras which can detect people at night, short-range communication like remote control and also in cookers for cooking food. These infrared waves can also cause burn to the skin.