If the sun is a big ball of fire why can't we make our own sun with a big ball of fire

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?

The energy of a photon was found to be 3.38 × 10–19 j. planck’s constant is 6.63 × 10–34 j • s. which color of light corresponds to this photon?

The freezing and boiling point of a substance changes as the air pressure around it changes. for example, at a lower air pressure (higher altitude) it is easier for water molecules to escape from liquid into the air. in a high altitude city such as denver, colorado compared to a sea-level city such as houston, texas, water