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Orientational lighting

Page history last edited by Vivien Tsao 6 years, 10 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.

 

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

Color: Red

V=IR

R=V/I

R=5V / 30mA

R=.1666 mOhms

-0.5: Did not account for Vf.

 

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, so lowering the resistance would increase the current and blow out the led.

 

 

c. What is the resistance range of the potentiometer?

 

+++

?? -1

 

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

 

So long as they all stay in series, then it does not matter. This is due to the face that starting the circuit does not supply all of the electrons, it pushes the ones that are present to follow a path. This then makes it so that there will be an equivilent resistance throughout the series, regardless of the order.

 

+++

R=V/I

R=9V/30mA

R=0.300 mOhms

-0.5 Did not account for Vf on the LED...

 

-1 for video...

Comments (1)

Vivien Tsao said

at 6:11 pm on Jul 11, 2013

Good job! Remember to account for the voltage drop across the LED! Also, remember to include the video next time. :]

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