Resistors

THEORY
 A resistor is one of the electical component which resists the flow of the current. The resistor has two terminals(legs) and there is no polarity in a resistor. When the current flows from one terminal to another terminal, the voltage dorp is produced between two terminals in a circuit. Therefore, the resistor is used to protect the electric device from damage of higher voltages.
The resistors have various values and thery are measured by ohm's range of a multimeter. In addition, there are four or five colour bands on the surface of a resistor. These colour bands indicate the resistance values.

EXPERIMENT
No. 1 Identifying, Testing and Troubleshooting Semiconductor Components
- Identifying, Testing and Combining Resistors  

• First two or three bands may be the numbers to write down
• Next band is the multiplier (how many zeros to add to the number)
• Gold multiplier makes one decimal place smaller, Silver makes two decimal places smaller
• Last band to right may be tolerance values
• Notice the examples on the right
• Brown, red, red = 1, 2, 100, 5% = 1200Ω 5%, or 1.2KΩ,1K2

 Some people use this saying to help them remember the colours:

Obtain 6 resistors of different values. You are then going to determine their value two ways:
· Use the colour code to calculate the value of the resistor.
· Include the maximum and minimum tolerance value of each resistor.
· Then measure the resistor value with a multimeter.Record the values in the chart below:

Value (colour codes )                                                               Value (multimeter)

1. yellow violet black brown 470Ω 1% (465.3 ~ 474.7Ω)                   467Ω

2. brown black red gold 1000Ω 5% (950 ~ 1050Ω)                           980Ω

3. green blue red gold 5600Ω 5% (5320 ~ 5880Ω)                           5.54kΩ(5540Ω)

4. brown black brown gold 100Ω 5% (95 ~ 105Ω )                           97.8Ω

5. brown black orange gold 10,000Ω 5% (9,500 ~ 10,500Ω )           9.83kΩ

6. brown black yellow gold100,000Ω 5% (95,000 ~ 105,000Ω )       99.6kΩ

Choose two resistors and record their individual ohm resistance value measured with a multi-meter:
Resistor 1 468 Ω     Resistor 2 10.01 kΩ

Put these two resistors together in series (end to end, one right after another) calculate and then measure their combined value. Show workings:

Calculated value 1 and 2 in series: 10.478 kΩ 
RT=R1+R2...
RT= 468+10,010=10,478Ω =10.478kΩ
Measured value 1 and 2 in series: 10.478 kΩ

Put these two resistors together in parallel (connect both ends when they are side-by-side). Calculate and then measure their combined value. Show workings:

Calculated value 1 and 2 in parallel: 0.45 kΩ
1/RT=1/R1+1/R2
1/RT= 1/468+1/10,010=21.39/10,010+1/10,010=22.39/10,010
RT= 447.1=0.45kΩ
Measured value 1 and 2 in parallel: 0.44 kΩ

What principles of electricity have you demonstrated with this? Explain:
 When the resistors are connected in series, the resistor's values are just added together. This circuit shows "RT=R1+R2..." formula with its principle. As a result, total resistance value increases. However, in parallel circuit, which uses "1/RT=1/R1+1/R2..." formula. Therefore, the total resistance value is lower than the lowest resistor in the parallel circuit. This principles are demonstrated by actual measurement and the measured values are nearly same as the calculated values.