Which observation supports the idea that light is made of particles?

A:Light is produced by the interaction of magnetic and electric fields.

B:Light spreads out after passing through an opening.

C:Light diffracts when it hits a barrier.

D:Light moves in a straight path.

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?

Astronomers studying the planet of rhombus have detected sedimentary rock on its surface. one astronomer wonders if material in this sedimentary rock used to be in igneous rock deep in rhombus’s interior. can igneous rock become sedimentary rock? explain your answer.