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resistor

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Secondary Information

Definition

A resistor is an electrical component that resists the flow of electrical current. It is a passive two-terminal device that is used to reduce current flow, adjust voltage levels, and divide voltages. Resistors are made of materials with high resistivity, such as carbon, metal, or semiconductor.

The resistance of a resistor is measured in ohms. The higher the resistance, the more the resistor resists the flow of current. Resistors are typically colour-coded to indicate their resistance value.

Resistors are used in a wide variety of electrical circuits. They are used to:

  • Control the amount of current that flows through a circuit
  • Convert electrical energy into heat
  • Divide voltages
  • Attenuate signals
  • Protect circuits from damage

How can the word be used?

The resistor was made of a material with a high resistance.

resistor

Different forms of the word

Noun:

  • an electrical component that resists the flow of current.

Etymology

The word "resistor" comes from the Latin word "resistere", which means "to stand against".

The first recorded use of the word "resistor" in English was in the 19th century.

Question

What is a resistor?

AQA Science Exam Question and Answer

Question:

Define what a resistor is in the context of electronics and explain how it influences the flow of electric current in a circuit. Provide an example of a practical application where resistors are used.

Answer:

A resistor is an electronic component designed to introduce a specific amount of resistance into an electrical circuit. It restricts the flow of electric current, converting electrical energy into heat energy. Resistors are commonly used to control the amount of current flowing through a circuit and to manage voltage levels.

In a circuit, resistors influence the flow of electric current according to Ohm's law (V = I × R), where V is voltage, I is current, and R is resistance. Increasing the resistance reduces the current for a constant voltage, and decreasing the resistance allows more current to flow. This relationship enables precise control over current levels and helps protect components from excessive currents.

An example of a practical application of resistors is in LED circuits. Light-emitting diodes (LEDs) are sensitive to voltage variations. Using a resistor in series with an LED helps regulate the current passing through the LED, preventing it from burning out due to excessive current. This application ensures consistent brightness and extends the LED's lifespan.