Case: Read the passage and answer the following questions

Historically the credit for the discovery of the fact that amber rubbed with wool or silk cloth attracts light objects goes to Thales of Miletus, Greece, around 600 BC. The name electricity is coined from the Greek word ‘electron’ meaning amber. Many such pairs of materials were known which on rubbing could attract light objects like straw, pith balls and bits of paper. For example, cut out long thin strips of white paper and lightly iron them. Take them near a TV screen or computer monitor. We can see that the strips get attracted to the screen. In fact, they remain stuck to the screen for a while.

When the bodies like glass or plastic rods, silk, fur and pith balls and so on acquire ……………… on rubbing.

An electrical energy

When bodies rub each other they gain static electrical energy.