Providing more routes
Physics Narrative for 14-16
Making any parallel connection increases the current
Adding more routes for the charge to take will result in an increased flow, so more current, as there will be less resistance. The same potential difference is available for each route, so, in addition to the current driven down the original route, there will be additional current for each route added. More charge is set in motion in each extra loop. The end result is that more loops lead to more charge in motion – a larger current in the battery. As the potential difference hasn't changed, this can only mean that the resistance of the entire circuit has dropped. As you add more routes, the resistance of the whole network falls further.
One step in analysing a circuit is to reduce it to a single loop: the whole network of resistors is replaced by a single resistor that results in the same current in the battery as the network it replaces. If the network is made with parallel connections, so providing additional routes, then the single resistor that replaces the network will always be of a lower value than any resistor in the network.