Explain why does a metal wire when connected to a cell offer resistance to the flow of current.
Current flows in a wire due to the flow of electrons in an opposite direction. Now there are some positively charged particles too. So when electrons flow from the negative electrode to the positive electrode through the metal wire. During their movement, they collide with free electrons and fixed ions of the wire. This causes them to lose their speed and change their direction. As a result, electrons slow down and drift towards the positive terminal. This is called resistance. (The obstruction offered to the flow of current).