Daniella Ellery, of Wairaki Primary School, asks :-

How does electricity go through power lines?

Neville Watson, an electrical engineer at the University of Canterbury, responded.

A power line consists of metal wires (called conductors) and poles that hold them up. Electrical current is the movement of electrical charge. This ability for charge to move is normally explained in terms of atomic structure and the strength by which electrons are bound to an atom. Some material allows charge to readily move through it (conductors) while others do not (insulators). All metals are conductors as they allow electrons to wander between the atoms. However, some metals are better than others in conducting electricity. Current does not flow until the ends of a conductor are connected to a power source, which causes a force on the electrons, causing them to move. This force (commonly referred to as voltage) is measured in Volts and can be created chemically, as in a battery, or moving a conductor through a magnetic field. It does not matter whether the magnet is stationary and conductor moves, or the magnet is moved and conductor stationary, it is the relative motion that generates a voltage (in most of New Zealand's power stations the magnets move).

An analogy is often made between water and electricity. The water is like the electrical charge and the water pressure is like the voltage. The water pipe is like the conductor. For a given size of water pipe the greater the water pressure the larger the water flow.