How do ATMs work? KENNETH LUI La Salle College ATMs (automatic teller machines) are a convenient way of getting money out of your account, depositing money or paying bills outside of banking hours and without having to queue for a long time.
To use an ATM, you insert your card and punch in your personal identification number (PIN). Your bank card has a magnetic strip on the back which is read by a card reader inside the machine. The reader sends the information it has read - your bank account number - together with an encoded version of the PIN you typed in - to the bank's central computer. The computer checks the account number and PIN to make sure they are correct. If they are, it allows you to continue.
If you want to withdraw cash, an electric eye next to the cash dispensing mechanism counts each bank note and keeps a record of all withdrawals in case of complaints and for the bank's records.
Inside the cash dispenser there is also a sensor which checks the thickness of each note so that it does not give out two notes stuck together, unfortunately. It rejects suspect notes, which are sent to a reject bin to be checked by bank staff.
Is it a coincidence that the moon takes the same time to orbit Earth and revolve on its own axis? It is not strictly accurate to say the moon revolves around the Earth. In fact, they both revolve around the centre of gravity of the moon-Earth system. Since this centre of gravity lies 4,800 kilometres from the Earth's centre, it is still inside the Earth. So for everyday purposes it is usually OK to say the moon revolves around the Earth.
The moon takes 27.3 Earth days to orbit Earth. This is the same time the moon takes to rotate once on its own axis, so we always see the same side of the moon.
