The sparse area surrounding a spiral galaxy is called a

The two most prominent wavelengths in the light emitted by a hydrogen discharge lamp are 656 nm(red) and 486 nm (blue). light from a hydrogen lamp illuminates a diffraction grating with 520lines/mm , and the light is observed on a screen 1.5m behind the grating. part a what is the distance between the first-order red and blue fringes? express your answer to two significant figures and include the appropriate units.

Which of the following correctly describes the early view of catastrophism?

The image shows a pendulum in simple harmonic motion the pendulum starts at a and swing to e