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# EE47: Lab 1

last edited by 5 years, 3 months ago

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.

V/I=R

(5-2.2)/.025 = 2.8/.025 = 112 ohm

Using a green LED, I need a resistance of 112 ohms.

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.

Lowering the resistance would also raise the current. Ergo, the resistance above is minimum resistance.

c. What is the resistance range of the potentiometer?

~0-10 kOhm

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

No, the circuit is in a series. Ergo, everything is "added up", and like addition, it can be done in any order.

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

(9-2.2)/.25 = 6.8/.025 = 272 ohm