Which kinds of objects emit visible light in the electromagnetic spectrum?
1)all objects
2)radioactive objects
3)relatively cold objects
4)relatively hot objects

Answer : Relatively hot objects

Explanation : We know that, the temperature of the objects is inversely proportional to their wavelengths. The objects emitting radiation in the visible region have short wavelength and hence are relatively hotter.

We know the range of wavelength of the visible spectrum is from 400 nm to 780 nm.

The correct answer is relatively hot objects.

Explanation:

Electromagnetic spectrum is a continuum of all the electromagnetic waves. They are arranged according to frequency and wavelength.

All objects emit wave according to their temperature.

The relatively hot objects emit the visible light or ultraviolet radiations having higher frequencies while the relatively cold objects emit wave of lower frequencies such as radio wave. The visible lights in the electromagnetic spectrum is seen by naked eyes.

The wavelengths of the visible light lies between 400 nm to 700 nm.

Therefore, the correct answer is relatively hot objects.

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