Question

why do you have to clean the ends of wire used for making circuit with in sand paper to make the bulb shine​

Answer 1

Answer:

Since wire is made of a metal, it reacts with the oxygen in air and forms a layer of oxide, when kept in open. Therefore, if the ends of the wire are oxidised, the metal or conductor does not remain in contact with the terminals of bulb or battery. Hence, the circuit remains incomplete or obstructed. Thus, we clean the ends of the wire with a sandpaper to remove the oxide layer and to allow the current to flow, so that bulb will glow.