3.7.2

Diodes, LDRs & Thermistors

Test yourself

Diodes

A diode is a component that only allows current to flow through it in one direction.

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Diodes

  • A diode is a component that only allows current to flow through it in one direction.
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Rectifiers

  • A rectifier is a component that turns an alternating current (repeatedly changes direction) into a direct current (one direction).
  • Diodes act as rectifiers as they block the alternating current when it changes direction.

Thermistors and LDRs

Thermistors and LDRs are devices where resistance changes with temperature or light. They can be used as switches for heaters and lights.

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Thermistors

  • A thermistor is a component where resistance changes with its temperature.
  • Usually, increasing temperature decreases the resistance.
  • We can use a thermistor to turn a heater off when a house reaches certain temperatures.
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LDRs

  • A light dependent resistor (LDR)s resistance changes with light intensity.
  • Usually, increasing light intensity decreases the resistance.
  • We can use LDRs to switch lights on when it gets dark or to know whether or not a camera phone needs to use “flash”.

Jump to other topics

1Principles of Science I

1.1Structure & Bonding

1.2Properties of Substances

1.3Cell Structure & Function

1.4Cell Specialisation

1.5Tissue Structure & Function

1.6Working with Waves

1.7Waves in Communication

2Practical Scientific Procedures and Techniques

3Science Investigation Skills

4Principles of Science II

4.1Extracting Elements

4.2Relating Properties to use of Substances

4.3Organic Chemistry

4.4Energy Changes in Industry

4.5The Circulatory System

4.6Ventilation & Gas Exchange

4.7Urinary System

4.8Cell Transport

4.9Thermal Physics

4.10Materials

4.11Fluids

5Contemporary Issues in Science

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