The Doppler effect applies to light waves as well as sound waves. Astronomers use this to measure the motion of stars and galaxies. In 1929, Edwin Hubble discovered that light from distant galaxies was shifted away from the blue end of the spectrum and towards the red end of the spectrum. Red light has a longer wavelength (and a lower frequency) than blue light. What could Hubble conclude about these galaxies?

A. The distant galaxies are growing smaller.
B. The distant galaxies are growing larger.
C. The distant galaxies are moving towards the Earth.
D. The distant galaxies are moving away from the Earth.

One kind of e-book display consists of millions of very small spheres that float in a thin fluid layer between two conducting transparent plates. each sphere is black on one side and white on the other, and possesses an electric dipole moment directed from the white side to the black. when an electric field is applied between the plates, the spheres rotate so that their dipole moment lines up with the field. depending on the fields direction, either the black or the white sides of th espheres can be made visible. the dipole moment of the spheres can be modeled as two opposite charges of magnitude 3.5 x 10^-15 c, separated by a distancce of 100 micrometers (um). what is the maximum possible torque on a sphere if the electric field between the transparent plates is 4.0 x 10^5 n/c