What the long streaks of bright light caused when a meteoroid gets close to the ground as it's burning up

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?

If y gets smaller as x gets bigger and y have an relationship?

Which of the following is part of the explanation or description of electromagnetic waves? (select all that apply) a. electrically charged molecules in a medium transfer their energy to nearby electrically charged molecules. b. a changing electric field causes a changing magnetic field. c. magnetic molecules in a medium transfer their energy to nearby magnetic molecules. d. a changing magnetic field causes a changing electric field.