1 / 17

RESISTORS

RESISTORS. Always remember…… V = IR (V= voltage in volts; I = current in amps; R = resistance in ohms). Special types of resistors. Diodes. A diode is a device which allows current to flow only in one direction. It is also known as a rectifier This is what a diode looks like.

makoto
Download Presentation

RESISTORS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RESISTORS Always remember…… V = IR (V= voltage in volts; I = current in amps; R = resistance in ohms)

  2. Special types of resistors

  3. Diodes • A diode is a device which allows current to flow only in one direction. • It is also known as a rectifier • This is what a diode looks like

  4. Diodes • This is the circuit symbol for a diode • Draw this symbol in your books • The arrow on the symbol shows the direction the current can flow.

  5. Diode • If the diode is reversed it acts like a very high value resistor and prevents current flow.

  6. Diode • Uses of diodes • Protecting equipment should the power be connected the wrong way round, • Converting a.c. into d.c.

  7. Light dependent resistor The LDR

  8. LDR • This is a resistor whose resistance depends on the amount of light falling on it.

  9. LDR • This is the circuit symbol for a diode • Draw this symbol in your books • The arrows represent light falling on the LDR

  10. LDR • When light falls on an LDR its resistance falls rapidly. • In low light or the dark – they act as high resistors. • In bright light they offer very little resistance Resistance of an LDR Light level

  11. LDR • LDR’s can be used to switch on street lights when light falls.

  12. Thermistors Temperature-dependent resistors

  13. Thermistor • This is a resistor whose resistance depends on the temperature.

  14. Thermistors • This is the circuit symbol for a thermistor • Draw this symbol in your books

  15. Thermisitors • Thermistors are used in circuits which are designed to be controlled by temperature, such as a sprinkler system.

  16. Investigating thermistors Temp Volts Amps Resistance oC V A ohms Calculate the resistance at 5 different temperatures

  17. Plot a graph of resistance against temperature for your thermistor.

More Related