Colored Light

Remove the incandescent lamp from its socket and place an LED in the LED holder.

With the LED in the circuit, adjust the potentiometer to vary the energy supplied to the LED. Measure the voltage for the LED. When you are finished you should answer the following questions once again.

1. What is the color of light emitted by the LED?
2. If the color of light changes with voltage, how does it change?
3. What is the threshold voltage of the LED and the voltage at maximum brightness?
4. How does brightness of the LED change with voltage?

Record and submit your measurements and observations. If the LED does not come on for any voltage, record that information and continue to the next experiment.

Color of Light Emitted by LED

Threshold Voltage (V)

Maximum Voltage (V)

Remove the LED from the circuit and reverse its connection to the socket. Repeat taking voltage measurements for the LED by focusing on the same four questions as before.

Explain the similarities and differences from the previous investigation.

Based on your results, answer the following questions.

1. What patterns do you see in your observations?
2. How is the incandescent lamp similar to LEDs?
3. How is the incandescent lamp different from LEDs?

Answer the questions in the space below.