OHM’S LAW 6

Ohm’sLaw Lab Report

Purpose

Theexperiment aims at investigating the three parameters involved in themathematical relationship referred to as Ohm’s law.

Overview

Inorder to accomplish this experiment the following were required acircuit experiment board, millimeter, D-cell battery, wire leads anda graph paper.

Thesetup of the experiment is as listed in the diagrams below

In first bit of this experiment,resistor were selected based on the color code. The circuit in figure11 was set up. The millimeter was the set to the range 200mA.Thecircuit was connected and the value of current was read and recordedfor each of the resistors that were selected for the experiment.

In the second bit, the voltageacross the resistors selected in the first part were measured bysetting the experimental equipment as illustrated by figure 12.Theresults were recorded in steps of five.

Results

The resultsfrom the experiment are recorded in the table below.

Resistance, |
Current, A |
Voltage, V |
Voltage /Resistance |

210 |
0.005 |
1.588 |
0.0076 |

230 |
0.0049 |
1.589 |
0.0048 |

560 |
0.0029 |
1.592 |
0.0028 |

820 |
0.002 |
1.593 |
0.0019 |

1000 |
0.0017 |
1.594 |
0.001593 |

Relationshipbetween current and voltage.

Sample calculation for the columnvoltage calculation

The graph of current againstvoltage is a straight line graph show in a linear relationshipbetween current, I and voltage V.As the resistance increases, thecurrent reduces this depicts an inverse proportional relationship between current and resistance.

Analysis

The relationship between currentand resistance is similar to that described by a straight linefunction y= -mx + c, which indicate a linear relationship between thevariable x and the variable y. In this experiment the values plottedon the y axis, current are line to those plotted on the x axis. Theslope of the graph from the plot of current versus resistance has anegative value, that is,

The negative sign shows thatcurrent and voltage are inversely related. As the amount ofresistance increase, the amount of voltage reduces in a proportionateway.

Ohm’s law states that voltageequals the product of current and the resistance, that is

Voltage= Current, I x Resistance

From this we learn that the ratioVoltage/Resistance is the value for current. Thus the columnvoltage/resistance in table 1 above is the calculated values forcurrent.

The difference between themeasured values and the calculated values for the second, third andfourth reading give a value of 0.0001 compare to those of the firstand the last readings. This indicates that the second, third andfourth reading were made with highly level of accuracy compared tothose of the first and last readings.

The graphshows inverse proportionality Current _{}1/Resistance

Let theconstant of proportionality be B.

Current = B x1/Resistance

B= Current xResistance

B = Voltage,therefore Voltage = Current x Resistance. The data from thisexperiment well agrees with this fact.

Possible sources of error in thisexperiment may include parallax error while taking readings from themeasuring instruments. And, use of un-calibrated equipment for thisexperiment. The two could only result to small margins of error.

Conclusion

It waspossible to accomplish the purpose of this experiment based on thedata obtained.There is a linear relationship between current, I andvoltage V. As the resistance increases, the current reduces and thisdepicts an inverse proportional relationship between current andresistance. This is captured by the statement of Ohm’s law, that isvoltage is the product of current and resistance.