When the wavelength of electromagnetic radiation is doubled, the energy of the radiation decreases. This relationship is described by the equation:
E = hc/λ
where E is the energy of the radiation, h is Planck's constant (6.626 x 10^-34 J*s), c is the speed of light (3.00 x 10^8 m/s), and λ is the wavelength of the radiation.
As the wavelength (λ) increases, the denominator of the equation becomes larger, which means the energy (E) decreases. This relationship is inverse: as the wavelength doubles, the energy is halved.
It's important to note that this relationship holds true for photons of electromagnetic radiation. Other factors, such as the frequency or intensity of the radiation, can also impact the energy of the radiation.