When atoms in a pure element are ❌ (given lots of energy) they give off light at fixed and ❌ frequencies. These frequencies directly relate to the colour - from low frequency ❌, through the visible spectrum, and up to high frequency ❌.

These emission line spectra are like a chemical ❌ for that element. They are caused by the movement of electrons between energy ❌ in the atoms. Hydrogen has the ❌ emission spectrum.

A ❌ will give off energy at a range of ❌, but there will be some gaps in it. The gaps in the spectrum from the Sun correspond exactly to the lines in the emission ❌ for hydrogen. This means that there is hydrogen present in the Sun, which is ❌ light of specific frequencies.

Boyle's Law states that ❌ is inversely proportional to volume. The pressure of a gas is caused by the ❌ colliding with the sides of the container, exerting a ❌ per unit of area. The pressure depends on the ❌ of collisions and the force of the particles’ momentum (which is ❌ as the gas is kept at a constant temperature). If the volume of the container ❌, there is half the amount of space for particles to move around in, making ❌ more likely. As the number of collisions ❌, so does the pressure.

A star begins its life as a ❌ of gas, which is mostly ❌ and helium. The particles experience a very weak attraction towards each other due to ❌.

As the gas cloud becomes ❌, the effect of gravity is to increase the ❌ and temperature. As more gas is drawn in by the increasing gravity, the mass of the cloud ❌ and therefore so does its gravity.

The increasing gravity ❌ the gas further so that it becomes hotter and denser. It eventually becomes a ❌star.

When the temperature and pressure become high enough, the hydrogen nuclei ❌ into helium nuclei, releasing large amounts of ❌. The star is now a stable ❌ star.

A star has a structure that in some ways is similar to the structure of our planet.

The core is the ❌ and most dense part of the star. This is where ❌ takes place and where high energy ❌ are released.

Energy is transported to the surface of the star by photons of ❌ energy and also via powerful ❌ currents (the movement of molecules in fluids, in this case energy transferred in the plasma).

The ❌ is the outer part of the star, where the photons are radiated into space.