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# Lab 1 Alex Lewis

last edited by 7 years, 10 months ago

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a.What resistance do you need to limit current to 30 mA (if using red LED) or 25 mA (if using yellow or green)? Be sure to state which color LED you are using. This resistance refers to the total resistance in series with the LED.

I am using a yellow LED. To find this out you would use Ohm’s Law. The Voltage from the battery is 5V and the LED uses 1.8V. the maximum current for the LED is 25mA.

V = I * R

3.2 = 0.025 * R

R = 128

Hint: Make sure that you account for the forward voltage drop (Vf) of the LED that you're using.

b. Is the resistance from question a) a maximum or minimum resistance? That is, in which direction if you change the resistance (higher or lower) would the LED likely fail.

It is a minimum resistance because any more current through the circuit would exceed the maximum of the LED and make it pop.

c. What is the resistance range of the potentiometer?

0 – 10,000 kilohms

a. Does it matter what order the components of your circuit are arranged between power and ground? Why or why not?

No, because the components are components are in a series it does not matter what order they are in.

a. Using this battery, what is the minimum resistance required for use with your LED?

Using the 9V battery and Ohm’s Law

R = 288

✓ calculation?