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Annie Scalmanini Lab 1

Page history last edited by Annie Scalmanini 13 years ago

Question 2:

2a. What resistance do you need to limit current to 20 mA?

V=IR
V = 5 volts
I = 20 mA

R = 5V/0.02A = 250 ohms

2b. Is 220 ohms a maximum or minimum resistance?

Minimum resistance.
(If we need a 250-ohm resistor to limit current to 20 mA, then the 220-ohm resistor will correspond to a larger current.)

2c. What is the resistance range of the potentiometer?

It was labeled as 0-10KΩ

Question 3:

3a. Does it matter what order the components of your circuit are arranged between power and ground? Why or why not?

Yes, the order of the components of my circuit between power and ground matters; for example, in the circuit diagram below,

Question 4:

4a. What is the minimum resistance required for use with the battery?

If we still want to limit forward current to 20 mA, and the battery supplies 9V, then the minimum resistance required for use with the battery is R = 9V/0.02A = 450Ω.

Comments (1)

Good work!
The resistor and LED are in series and hence the order of the components between the power and ground doesn't matter.
Please keep in mind that LEDs usually have a forward voltage drop when calculating the resistance required to protect the LED from being damaged by too much current. It is okay to ignore that in this lab.

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