What type of electromagnetic radiation is used in communications devices such as cellular telephones?

Antireflective coatings on solar cells are often made by applying a thin film of silicon nitride (sinx), which has an index of refractive of 1.2, on the top of the silicon solar cell, which has a refractive index of about 3.5. however, the sun emits radiation of various wavelengths which the solar cell absorbs, and the antireflective coating can only absolutely minimize the reflection of one of these wavelengths. the coating thickness is chosen to reduce the reflection of green/yellow light (e = 2.2 ev), which is the most intense color in the solar spectrum (shown below). which of the following coatings would minimize reflection of green/yellow light? the answer is 820 nm how? what is the angular width of the central maximum of an electron traveling at 2 x 108 m/s going through a single slit of width 1 mm.

According to piaget’s stages of cognitive development, the child does not differentiate between self and other objects. the child repeats rewarding activities, discovers new ways to get what he or she wants, and may have imaginary friends. which period is described?

Hi , i am new here can anyone me out with this question why is space black after having so many shining objects like sun , moon , stars