Question

What would you expect if a plastic ruller is rubbed vigorously with a woollen cloth

Answer 1

I shall expect that plastic rubber will get charged.

This results for it to attract paper pieces.

Such type of charging is called charging by friction.

Answer 2

" ᴄʜᴀʀɢɪɴɢ ʙʏ ғʀɪᴄᴛɪᴏɴ"

ɪғ ᴀ ᴘʟᴀsᴛɪᴄ ʀᴜʟᴇʀ ɪs ʀᴜʙʙᴇᴅ ᴠɪɢᴏʀᴏᴜsʟʏ ᴡɪᴛʜ ᴀ ᴡᴏᴏʟʟᴇɴ ᴄʟᴏᴛʜ , ᴛʜᴇ ᴘʟᴀsᴛɪᴄ ʀᴜʟᴇʀ ᴡɪʟʟ ɢᴇᴛ ᴘᴏsɪᴛɪᴠᴇ ᴄʜᴀʀɢᴇ ᴀɴᴅ ᴛʜᴇ ᴡᴏᴏʟʟᴇɴ ᴄʟᴏᴛʜ ᴡɪʟʟ ɢᴇᴛ ɴᴇɢᴀᴛɪᴠᴇ
ᴄʜᴀʀɢᴇ.

ᴀɴᴅ, ᴛʜᴜs ᴛʜᴇʀᴇ ᴡɪʟʟ ʙᴇ ᴄʜᴀʀɢɪɴɢ ʙʏ ғʀɪᴄᴛɪᴏɴ.