Wavelength of infrared radiations is

The correct option is "longer".

To understand why the wavelength of infrared radiations is longer, we can look at the organization of the electromagnetic spectrum. The electromagnetic spectrum is a range of all types of electromagnetic radiation, ordered by wavelength, frequency, and energy. The main regions of the spectrum, listed in order of increasing wavelength (which corresponds to decreasing frequency and decreasing photon energy), are:

1. Gamma rays
2. X-rays
3. Ultraviolet (UV) light
4. Visible light
5. Infrared (IR) radiation
6. Microwaves
7. Radio waves

Visible light represents a very small portion of the electromagnetic spectrum, with wavelengths ranging approximately from 400 nanometers (violet) to 700 nanometers (red). The term "infrared" literally means "below red" because its frequency is lower than that of red light (the lowest frequency and longest wavelength of visible light).

Because wavelength ($\lambda$) and frequency ($\nu$) are inversely proportional as described by the equation:

$c=\lambda \nu$

where $c$ is the constant speed of light, a lower frequency directly corresponds to a longer wavelength. Therefore, the wavelengths of infrared radiations are longer than those of visible light, extending from about 700 nanometers up to 1 millimeter.