Give Long Answers in not more than 100 words:
(a) Write a brief note on stars.
Answers
Answer:
A star is a very large ball of bright glowing hot matter in space. That matter is called plasma. Stars are held together by gravity. They give out heat and light because they are very hot.
Stars are hot because nuclear reactions happen inside them. Those reactions are called nuclear fusion. Nuclear fusion makes light and heat and makes bigger and bigger chemical elements. Stars have a lot of hydrogen. Nuclear fusion changes hydrogen into helium. When a star gets old, it starts to change the helium into other bigger chemical elements, like carbon and oxygen. Fusion makes a lot of energy. The energy makes the star very hot. The energy produced by stars moves (radiates) away from them. Much of the energy leaves as light. The rest leaves as other kinds of electromagnetic radiation.
The smallest stars (red dwarfs) fuse their hydrogen slowly and live for 100 billion years. Red dwarfs live longer than any other type of star. At the end of their lives, they become dimmer and dimmer. Red dwarfs do not explode