Identifying resistor values

image from datasheetoo.com

09/03/2011
key:
B=Black
Br=Brown
R=Red
O=Orange
Y=Yellow
G=Green
L=Blue
V=Violet
Gr=Grey
W=White
Gold=5% Tolerance
Silver=10% Tolerance
    
The task which i carried out today was to calculate the values of 6 different resistors with various colour bands and then check the value with a multimeter and see if the two values match up.

one of the resistors i calculated

From left to right: Br-B-O

• 1st i wrote down the the number which represents Brown (1)
• 2nd I wrote down the number which represents Black (0)
• then the next colour which is orange is the multiplier and because its orange it means i had to multiply it by 100 (add to zeros to the 1 and 0) which gives the total of 10000ohms (10Kohm).
• the last band which is gold is the tolerance percentage that the calculation of the 1st 3 bands can be within, in this case gold is 5%.

the next task was to measure the resistors with a multimeter to get an acurate reading and to see if it is within the 5% tolerance e.g. (as for above resistor) the reading was 9998.3 ohms. To work out if this was within the 5% tolerance i used this calculation 5/100x10000ohms=500ohms so because the reading on the multimeter was 9998.3ohms this was well within the 5% .

Next i picked two random resistors from the original six and connected them in series and measured them with a multimeter on the resistance setting. Acording to ohms law, total resistance in series is the sum of all resistances in the circuit. the calculated resistance for the two resistors in series was 125.7ohms and the measured value was 125.3.Next i put the two previous resistors in parallel and the calculated value was 21.2ohms and then i measured it next with a multimeter and got a reading of 21.4ohms, to calculate the resistance u hav to apply kirchoffs law Rt=R1+R2
                                                              =98.7+27
                                                              =125.7ohms
                                               
Next i used the same value resistors as i did in the series circuit as above except now i put them in parallel and calculated the resistance and then measured it with a multimeter. Because the two resistors are now in parallel the law of resistance is different, the formula i used was1/Rt=1/R1+1/R2
                                                                                                     =1/98+1/27
                                                                                                     =0.01020408+0.03703704
                                                                                                     =0.04724112
                                                                               1/0.04724112=21.1679994
                                                                                                  Rt=21.17ohms