The blue end of the visible color spectrum has wavelengths, and the red end has wavelengths.

Blue end has shorter wavelength and red end has longer wavelengths.

Explanation:

Visible region consists of Violet, Indigo, Blue, Green, Yellow, Orange and Red. These colors are arranged in the order of increasing wavelengths which means that blue region has shorter wavelength and as we move towards red region, the wavelength of light increases.

Blue region has shorter wavelength and higher frequency whereas red region has longer wavelength and smaller frequency.

Frequency and wavelength follow inverse relation.

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.