Electronic – Power that is consumed by diode

circuit analysisdiodespower

I’m wondering if I’m making the right approach when I’m trying to calculate the power consumed by the diode in the circuit.

Here is the problem:

enter image description here

So my approach is:

Power loss by diode
$$V_f \times I_f$$
where

\$V_f\$ = Diode forward voltage drop.

\$I_f\$ = The current flowing through the diode.

So the first thing I did was to calculate the current

$$I = V/R = 5/1000 = 5 mA$$

And then I use
$$
V_f \times I_f= 2 \times 0.005 = 10 mW
$$

Is this correct?
I feel like there is more to the problem with the fact that it states ”red color light”. Should I check on a sheet or similar?

Best Answer

I think that you have neglected the voltage drop across the diode which limits the current.

My solution is : $$ \because V_{R_1}=V_0-V_f=5-2=3\,\text{V} $$ $$ \therefore I_f=I_{R_1}=V_{R_1}/R_1=3/1000=3\,\text{mA} $$ $$Power Loss =V_f\times I_f=2 \times0.003=6\,\text{mW} $$

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