How many black holes are there in the andromeda galaxy?

The magnitude of the poynting vector of a planar electromagnetic wave has an average value of 0.939 w/m^2 . the wave is incident upon a rectangular area, 1.5 m by 2.0 m, at right angles. how much total electromagnetic energy falls on the area during 1.0 minute?

Use 4 to 5 complete sentences, explain the concepts of beats and how beats are produces.

3. which is not a primary color of light? blue red green yellow