Electrical circuits labExperiment 3

Resistors, Potentiometer, and Rheostats

Prepared by :Eiad Nadi Nemer

Supervised by : Eng. Anas abd-alqaderIntroduction:in this experiment we talk about the resistors and how measure resistance.As discrete component, resistors com in various sizes and shapes depending on their power rating and use.The resistive element material may also vary, metallic , wire, carbon. The resistor most commonly used in the laboratory is made of carbon encased in a tubular form with axial leads.Objectives: gain familiarity with available type of resistors, potentiometer and rheostat. Determine the nominal value of resistance using color code, and the actual value using different type of measurement. Determine the linearity of a potentiometer and use it is a voltage divider or control element.Equipment: Digital multi meter Potentiometer Rheostat The position boxAnalysis& data and result:We have kind to solve value of resistance:1. Color code calculate2. Ohm meter3. Ohms low4. Wheatstone bridgeFor color code:

A: first significant digit.B:second significant digit.C:multiplierD:tolerance.The color taken in this table:BlackBrownRedOrangeYellowGreenBlueVioletGraywhit

01234567810

The color of tolerance :GoldSilverNo color

5%10%20%

The value of R=(10A+B)*10^CD.*Ohmmeter:By connect the resistor in parallel with it without any sources connected to the resistor.*ohms law:To find the current in deferent value of voltage I=V/R.Wheatstone bridge:Thats by using three resistor know value to find one unknown value Rx=(R2*R3)/R1.We have a 3 resistor and we find the value of it:ResistorColor codeExpected valueMeasured value

1Brown-black-red-gold10*1025%0.989Kohm

2Brown-black-yellow-gold10*10450.0997Mohm

3Yellow-violet-orange-gold47*10350.04707Mohm

We have 5 value of variable resistance:PositionVariable resistance

0%0.059ohm

25%2.36kohm

50%5.247Kohm

75%7.80Kohm

100%9.7766Kohm

Graph of position and the variable resistance:

Conclusion:We seen in this experiment we can get the value of resistance by color code but we find the error between the measured value and expected value and we seen the position and variable resistance graph is linear.