What is a resistor and how does it work?
Devices called resistors let us introduce precisely controlled amounts of resistance into electrical circuits. Photo: Four typical resistors sitting side by side in an electronic circuit. A resistor works by converting electrical energy into heat, which is dissipated into the air.
A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to provide a specific voltage for an active device such as a transistor.
- resistors are made from small rods of ceramic coated with metal such as a nickel alloy or a metal oxide such as tin oxide. The value of resistance is controlled by the thickness of the coating layer; the thicker the layer, the lower the value of resistance.
- Devices called resistors let us introduce precisely controlled amounts of resistance into electrical circuits. Photo: Four typical resistors sitting side by side in an electronic circuit. A resistor works by converting electrical energy into heat, which is dissipated into the air.
- A resistor is used to reduce the flow of electricity in an electric circuit. Resistors come in fixed or variable types. A fixed resistor cannot be changed as it is set at a specific value, whereas a variable resistor can manage flows at and below a specific level.
The main function of resistors in a circuit is to control the flow of current to other components. Take an LED (light) for example. If too much current flows through an LED it is destroyed. So a resistor is used to limit the current.
- Voltage varies directly with current. "R" is the constant of proportionality telling how much it varies. If I add in a resistor to a circuit, the voltage decreases. If you have a resistor in a circuit, with a current flowing through it, there will be a voltage dropped across the resistor (as given by Ohm's law).
- Capacitors store electric energy when they are connected to a battery or some other charging circuit. They are commonly placed in electronic components and are used to maintain a power supply while the device is unplugged and without a battery for a short time.
- A capacitor is a passive two-terminal electrical component that stores potential energy in an electric field. The effect of a capacitor is known as capacitance. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy.
In short: Resistors limit the flow of electrons, reducing current. Voltage comes about by the potential energy difference across the resistor. The mathematical answer is that a resistor is a two-terminal electric device which obeys, or you could say enforces, Ohm's law: V=IR.
- The voltage dropped by a resistor is given by Ohm's Law: V = I R. So if you know exactly how much current your device will draw, you could choose a resistor to drop exactly 7.5 V, and leave 4.5 V for your device, when that current is run through it.
- Converting 220 volts to 110 volts is possible. You can convert 220 volts to 110 volts by either using an adapter plug or removing the existing 220 receptacle from the outlet box.
- In a series circuit, adding more resistors increases total resistance and thus lowers current. But the opposite is true in a parallel circuit because adding more resistors in parallel creates more choices and lowers total resistance. If the same battery is connected to the resistors, current will increase.
Updated: 3rd October 2019