Circuits

# In which circuit does a current follow more than one path?

In just about all of them. The idea of current flowing in a loop is a lies to children simplification. In anything more complicated than a torch or a doorbell, the elctricity flows along many different paths.

The grown-up version is embodied in Kirchhoff's laws:

1) The algebraic sum of the currents entering a node is zero.

Algebraic sum here means that if you arbitrarily call currents entering a node positive, and currents leaving the node negative (or vice versa) and add them all up, it always comes to zero. It's just a fancy way of saying that the total current coming in is equal to the total current going out. In other words, a node (any single point in a circuit) does not store charge.

2) The algebraic sum of the voltages around a given loop is zero.

Algebraic sum here means that you arbitrarily choose a direction around the loop. Increases in voltage as you traverse the loop are counted as positive, decreases as negative. It's just a cute way of saying that all the positive voltages are cancelled out by negative voltages.

Now, if you ever see a circuit diagram for your TV set or whatever, you won't be expecting a single path for the electricity to flow around!

But in simple circuits like the circuit in a flashlight, there is only one current path.