All are examples of electromagnetic energy except <span>circles forming when a rock drops into a pool. The correct option among all the options that are given in the question is the third option or option "C". The other choices can be negated. I hope that this is the answer that has actually come to your help.</span>
When you rub inflated balloon with your hair or your kitten's fur, charge is induced on all over the balloon's surface. This is called "charging by friction" because you developed charges by rubbing to bodies with each other. It will also stick on your wall you can check it out. This is because of "unlike charges attract each other". Rubbed balloon and wall possessed unlike charges which made them stick together.
In refraction, when a wave travels from one medium to another it changes speed.
Correct option is A.
When the core of a star like the sun uses up its supply of hydrogen for fusion, the core begins to contract in size. The gravitational forces becomes strong and cause the star to reduce in size. as the star contracts, the temperature of the star also rises since the heat is distributed inside smaller Volume now.