The battery holds electric charge and has a voltage which can be thought of as like water pressure: When the switch is on, the battery voltage makes the current flow.
What is the difference between a battery and a current?
A fully charged battery is like a full tank of water. A flow of electricity is called current because it is similar to a current of water: The electric current (measured in Amps) is like the flow rate of water. Voltage (measured in Volts) is like water pressure. More voltage gives more current! No voltage, no current.
Why do we use analogies to describe current and voltage?
As it is hard to visualise current and voltage, analogies are often used to describe these concepts. When using analogies it is important to consider the limitations of each analogy to avoid misunderstanding. Current is to do with the rate of flow of charge.
The voltage of a battery is also known as the emf, the electromotive force. This emf can be thought of as the pressure that causes charges to flow through a circuit the battery is part of. This flow of charge is very similar to the flow of other things, such as heat or water. A flow of charge is known as a current.
How do Analogies help us understand basic electric ciruits?
The nature of the analogies can help develop an understanding of the quantities in basic electric ciruits. In the water circuit, the pressure P drives the water around the closed loop of pipe at a certain volume flowrate F. If the resistance to flow R is increased, then the volume flowrate decreases proportionately.
This flow of charge is very similar to the flow of other things, such as heat or water. A flow of charge is known as a current. Batteries put out direct current, as opposed to alternating current, which is what comes out of a wall socket. With direct current, the charge flows only in one direction.
How is voltage represented in equations & schematics?
Voltage is represented in equations and schematics by the letter “V”. When describing voltage, current, and resistance, a common analogy is a water tank. In this analogy, charge is represented by the water amount, voltage is represented by the water pressure, and current is represented by the water flow. So for this analogy, remember: