Jan 192011

Starting out with a beginner’s LED circuit:

simple led circuit, light an led

A schematic of a simple led circuit

Remember DO NOT GO HIGHER THAN 9 VOLTS for this circuit (whether using a battery or power supply)!

RESISTOR (470 ohms) – this drops the 9 volts from your source down to a good level for your LED.
LED – this is a diode that only lets current flow in one direction, but it also gives off light  (Warning! Putting more than 3v through a LED may kill it. They can shatter, so use a resistor in series with it!)

Simple LED circuit using a breadboard

Simple LED circuit using a "breadboard".

The LED is a “polar” component – electrons enter a LED through the cathode leg of the LED. If the LED doesn’t light, it may be in backwards. Make sure the flat side of the LED is facing your “negative wire” or ground.

LED circuit Questions:

  1. Use a picture editor to draw a red line on the graphic showing the path of the electricity (Think: Electrons begin moving from the negative pole of your supply, through the circuit components, and back to the positive pole  (this may seem opposite to conventional current).
  2. measure and record the voltage of your power source
  3. measure and record the voltage drop across the resistor
  4. measure and record the voltage drop across the LED
  5. add up the voltage for of everything except your source
  6. what is the relationship between the source voltage and the total of your voltage drops?

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