LEDs are fragile and can only have a certain amount of current flowing through them before they burn out. At the bottom of this tank there is a hose.įor this experiment, we want to use a 9 volt battery to power an LED. So for this analogy, remember:Ĭonsider a water tank at a certain height above the ground. 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. When describing voltage, current, and resistance, a common analogy is a water tank. Voltage is represented in equations and schematics by the letter 'V'. The unit 'volt' is named after the Italian physicist Alessandro Volta who invented what is considered the first chemical battery. It is measured in volts, which, technically, is the potential energy difference between two points that will impart one joule of energy per coulomb of charge that passes through it (don't panic if this makes no sense, all will be explained). This difference in charge between the two points is called voltage. We define voltage as the amount of potential energy between two points on a circuit. So, let's start with voltage and go from there. Ohm starts by describing a unit of resistance that is defined by current and voltage. Georg Ohm was a Bavarian scientist who studied electricity. Components in the circuit allow us to control this charge and use it to do work. A circuit is a closed loop that allows charge to move from one place to another. So, when we talk about these values, we're really describing the movement of charge, and thus, the behavior of electrons.

Resistance is a material's tendency to resist the flow of charge (current).

Current is the rate at which charge is flowing.

Voltage is the difference in charge between two points.

The three basic principles for this tutorial can be explained using electrons, or more specifically, the charge they create: They all operate using the same basic power source: the movement of electrons. Your lightbulb, your stereo, your phone, etc., are all harnessing the movement of the electrons in order to do work. Electrons create charge, which we can harness to do work. Your browser does not support the audio element.Electricity is the movement of electrons.

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A multimeter can measure several functions including voltage, current, resistance, and temperature. An ohmmeter is used for measuring resistance.

The tool for measuring volts in an electric circuit is called a voltmeter.

The concept behind Ohm's law was first explained by German Physicist Georg Ohm who the law is also named after.

In AC circuits, because the current is constantly changing, other factors such as capacitance and inductance must be taken into account.

It is generally applied only to direct current (DC) circuits, not alternating current (AC) circuits.

What is the voltage V in the circuit shown? If the voltage across a resistance is doubled, what will happen to the current?Įxplanation: If you look at the equation V= IR, if R stays the same then if you multiple V*2 (double the voltage), you must also double the current for the equation to remain true.ģ. If the resistance of an electrical circuit is increased, what will happen to the current assuming the voltage remains the same?Ģ. More water will flow through the pipe (current) the more pressure is applied (voltage) and the bigger the pipe is (lower the resistance).ġ. The voltage is the water pressure, the current is the amount of water flowing through the pipe, and the resistance is the size of the pipe. One way to think of this is as water flowing through a pipe.

Ohm's law describes the way current flows through a resistance when a different electric potential (voltage) is applied at each end of the resistance.

Define current voltage resistance