Which one of the following statements is not correct ?

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The longest wavelength of light visible to human eye is about 700 nm

The shortest wavelength of light visible to human eye is about 400 nm

The wavelength of gamma rays is longer than that of X-rays

The ability of a telescope to form separable images of close objects is called its resolving power

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC NDA-2 – 2016

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The electromagnetic spectrum is ordered by wavelength (or frequency/energy). Moving from shorter wavelengths to longer wavelengths, the order is typically Gamma rays, X-rays, Ultraviolet, Visible light, Infrared, Microwaves, Radio waves. Therefore, gamma rays have shorter wavelengths than X-rays. The statement that the wavelength of gamma rays is longer than that of X-rays is incorrect.

Order of electromagnetic spectrum components by increasing wavelength: Gamma < X-ray < UV < Visible < IR < Microwave < Radio.

Statements A and B are correct descriptions of the approximate range of wavelengths for visible light, with red light (around 700 nm) having the longest wavelength and violet light (around 400 nm) having the shortest. Statement D provides a correct definition of resolving power, which is an important characteristic of optical instruments.

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