# diode in parallel with resistor

Discussion in 'Homework Help' started by u-will-neva-no, Apr 26, 2011.

1. ### u-will-neva-no Thread Starter Member

Mar 22, 2011
230
2
Hello, I have attached an image and am required to find the current through the diode (Id) and and the current flowing through the resistor (Ir).

Im using KCL so I have Is -Ir - Id=0 (where Is is the current source)

10mA -Ir -Id =0
Ir + Id = 10mA

I dont know where to go from here however...I want to use ohms law to obtain another equation but due to no voltage source Im not sure...

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2. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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3. ### bluemarvin New Member

Apr 19, 2011
8
2
The diode sets the voltage across the resistor...the voltage across both must be equal. If for some reason, voltage across the R and D climbed higher, more current would flow through the diode thus dropping the voltage back to .7V. Therefore the current through the resistor must be .7V/200R =3.5mA. Since you are driving both the resistor path and the diode path with a 10 mA current source, the rest of the current must flow through the diode, therefore it's passing 10-3.5mA=6.5mA.

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4. ### u-will-neva-no Thread Starter Member

Mar 22, 2011
230
2
Thanks you two!