Q:

# What is the function of a resistor?

A:

A resistor is a specialized electrical component that provides resistance as a circuit element. Resistors are passive, which means they are not affected by the current they carry.

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Resistors have two primary functions within a circuit:

• Reduce current flow
• Lower voltage

Resistors are usually made of metal or carbon wire. They are designed to keep a constant value when in use and produce heat instead of light when used inside an electrical component. As the circuit works, resistors dissipate heat, which is not used. On the other hand, the metal portion of a light bulb is a type of resistor that does emit light.

There are three types of resistors:

1. Fixed
2. Variable
3. Special

Fixed resistors are the most common. They can be found inside many different types of electronic components and serve to protect them from too much current flow.

Traditional variable resistors are continually altered as they work. A common type of variable resistor is found in the volume control on a radio. Another type of variable resistor is called a potentiometer, or a pot. Pots are usually small and work by having their resistance control adjusted once and fixed, often with a screwdriver.

Two common types of special resistors include light-dependent resistors, which change resistance as light levels change. Similarly, thermistors change resistance as the temperature changes.

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## Related Questions

• A:

A transistor works by changing its resistance between the amount of power going in and the power going out, depending on how much current flows through the base to the emitter. Transistors can amplify electronic signals and precisely control the amount of current going through the circuit.

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• A:

A shunt resistor works by measuring either direct or alternating current that flows in an electrical circuit through the voltage drop that is generated across the resistance. Also known as a current shunt or ammeter shunt, this precision device uses the principle of Ohm's Law, which is mathematically represented by the equation V = I x R, where "V" indicates voltage, "I" denotes current and "R" is resistance. The standard units for voltage, current and resistance are volts, amps and ohms, respectively.

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A light dependent resistor, or LDR, varies resistance in a circuit based on how much light shines on it. When fully illuminated, the LDR has no resistance and current flows freely, but with darkness the resistance increases and current flow stops. In most circuit designs, the LDR acts like an on/off switch based on how much light shines on it.