Laboratory #2 Biasing

    This lab that we worked on last night was using two LEDs and trying light them up appropriately and efficiently.

Before we did the experiment, we calculate all the data that we need in the lab. First were the two resistance of  tow LED's. Rled1=219.78 ohms   Rled2 =100 ohms. According to the equivalent circuit in the lab book which the LEDs in parallel, we calculated the two resistance R1 and R2 which would share some voltage from the LEDs. R1=175.842 ohms R2=350. Because we could not get the exact resistor, we just get the close ones which were 148 ohms and 353 ohms. Then, we set the circuit as the image and recorded all the data for doing the further calculation. We had the current and the voltage of the led one were 15.5 mA and 6.69V. The current and the voltage of the LED two were 21mA and 1.64V.
Question: a.(Fig 2) 0.2 A-hr/(0.02275A+0.02A)= 4.678 hours
                b. LED 1 %Error = (15.5mA -22.75mA) /22.75mA *100%= 31.86%
                    LED 2%Error=(21mA-20mA) *100% = 5%\
                c.  P1=0.0155A*6.69V=0.103695 W
                    P2=0.021A*1.64V = 0.03444W      
                    so Ptotal=0.138135 and the Psupply= 9V*0.0365A=0.3285W
                      The efficiency= (Ptotal/Psupply) *100%= (0.138135/0.3285) *100%= 42.05%
                d. if the battery change to 6V, the efficiency would go up. It because the Psupply go smaller and                                            
                    also the lost energy would go smaller too.
After this experiment, we should know if we want the equipment work efficiency, we better let it work in the appropriate voltage range.