An electric current is a flow of electrons through a conductor (like a copper wire). Since we can't see electrons, it would be nice to have a model or an analogy of electric circuits to help us understand circuits better. Water flowing through pipes is pretty good mechanical system that is a lot like an electrical circuit.
This mechanical system consists of a pump pushing water through a closed pipe. Imagine that the electrical current is similar to the water flowing through the pipe. The following parts of the two systems are related:
The pipe is like the wire in the electric circuit
The pump is like the battery.
The pressure generated by the pump drives water through the pipe; that pressure is like the voltage generated by the battery which drives electrons through the circuit.
The seashells plug up the pipe and slow the flow of water, creating a pressure difference from one end to the other. In a similar way the resistance in the electric circuit resists the flow of electricity and creates a voltage drop from one end to the other. Energy is lost across the resistor and shows up as heat.
