What is an Electron Gun??When a piece of metal is heated, electrons escape from its surface. These free electrons can be accelerated in a vacuum, producing a beam. The hot metal surface and the accelerating plates are sometimes called an ‘electron gun’....

Do you ever think why an object feels lighter when submerged in water??The answer is here:-                when we put any object in water it displaces water and displaced water volume  is equal to volume of body submerged in water....