do all the electronic equipments emit large amount of heat?

I think you will find that every device that uses electricity will emit heat. This is because no electronic device is 100% efficient, the wasted engery is always emitted as heat. The best that designers can do is to improve the efficiency but it will still never reach 100%. Some devices waste more energy than others, for example many TVs will get very warm as do computers, lightbulbs, hoovers etc. This additional heat is real problem in hot countries as it makes the air conditioning work harder.