What is Joule's heating effect?

The photoelectric effect was first observed by H.Hertz. What is photoelectric effect?

What is meant by chelate effect? Give an example.

The phenomenon of global warming is due to greenhouse effect. a) What is greenhouse effect? b) What are the consequences of greenhouse effect?

Many chemical properties of organic compounds can be explained on the basis of electron displacement effects. What is a resonance effect?

What is founder effect?