• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12

Investigate the relationship between the variables V, R, and I in an electric circuit.

Extracts from this document...


Experiment 3: Ohm’s Law                                                                    Date: 22.03.2004

Objective: 1) To investigate the relationship between the variables V, R, and I in an

                      electric circuit.

                  2) To analyze series and parallel connection in terms of V, R, I

                  3) To determine the relationship between current and voltage in a circuit that  

                      contain a filament bulb


It is known that electrons flow through a conductor metal wires with an ease without any resistance. This means that nothing would prevent the flow of the electrons. In a normal case however, under normal conditions, a resistance in the wire would affect the flow of the electrons in much the same way that friction slows down a sliding box on a platform. To allow more electrons to move against the resistance of a wire, it is necessary to apply a potential difference between the two ends. One can calculate the potential difference needed to create a current, I if the constant resistance, R of the wire is known. The relationship between these three variables (R, I, V) is given through Ohm’s Law which stated that the potential difference, V in a wire is proportional to the current, I if the temperature and all other physical quantities are fixed. From the law itself, we have an expression:


...read more.



  1. The resistor is remove the next one used is chosen. The voltage is recorded in Table 1 as in step 5. The process is continued until all the resistors’ voltage recorded.

Part 2: Resistance in circuits  

  1. Three resistor of the same value is chosen. The set of colours is recorded in Table 2.
  2. The coded value of the resistors is determined and the value is recorded in the column labelled “Coded Resistance” in table 2. The tolerance value is entered as indicated by the colour of the fourth band under “tolerance”
  3. The multimetre is used to measure the resistance of the three resistors. The value is then recorded in Table 2.
  4. The percentage experimental error for each resistance value is calculated and is recorded
  5. The three resistors are connected to the series circuit by using the spring clips on the Circuit Experimental Board to hold the leads of resistors together without bending them. The resistance of the combination is measured as indicated on the diagram by connecting the leads of the Multimetre between the points at the end of the arrows.


  1. A parallel circuit is constructed by using the combination of the two resistors and finally by using all the three resistors. The values for the circuits are measured and recorded.

Part 3: Voltage in circuits

...read more.


In part 2, the coded tolerance for the resistor is +5%. From the reading we obtain the percentage of errors is 1% and 2%. Thus it said that the data obtain is acceptable. In part 2, we conducted two experiment whereby in one experiment the resistor is arrange in series and in the other experiment the resistor is arrange in parallel. Base on the theory for series resistor we have:


Thus the equivalent resistance in the circuit is:


The rule for the total resistance when the resistor is arranged in parallel is as followed:


As a conclusion we can say that the data obtain in the experiment obey the rule.

        In part 3, we found out that the voltage gets distributed in a series circuit with equal resistance when the value of the resistor is the same. The larger the value of the resistor, the larger the value of the resulting voltage.

        In part 4, a voltage versus current was obtained. At a certain point in the graph, a straight line is obtain which directly prove Ohm’s Law which stated that the voltage, V is proportional to the current, I and the slope of the graph is the resistance.


        As a conclusion, we found out that the voltage, V is proportional to the current, I. The relationship for the variable V, I, R is V = IR

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Electrical & Thermal Physics essays

  1. Investigating the E.m.f and Internal Resistance of 2 cells on different circuit Structures.

    amps but I realised this was too inaccurate as the results were all rounded to the same value of 1 amps so therefore I decided to use milliamps which meant the current was measured to the nearest thousandth amp. This created more accurate results as the change in current was far more noticeable and therefore utilizable for the investigation.

  2. I am going to investigate what the resistivity is of a pencil lead. ...

    The reason I thought that temperature might have caused this was because I noticed that the pencil lead was warm by the end of the experiment. To prevent this from happening in the real experiment I will turn the power off after every reading to cut down the amount of time current is flowing through the pencil lead causing heat.

  1. physics sensor coursework

    �100 Error min = 4.12% At 900 lux: Max value = Max V/ Min I Max value = (4.16 + 0.005)/ [(18.73 - 0.005) �10^-3] Max value = 222.43 ? Min value = Min V/ Max I Min value = (3.89 - 0.005)/ [(18.78 + 0.005)

  2. Investigation into the resistance of a filament lamp.

    If the values are negative then you have connected ammeter and voltmeter wrong way. xv. You can change the value of the voltage across the lamp by changing the resistance of the variable resistor; this will also change the value of the current.

  1. The potato - a source of EMF

    excel so instead I drew the curves by myself using a flexi-curve ruler. This allowed me to minimize but not eliminate my error in drawing the curves by hand. However, the Maximum Power Graph can never be as accurate as a straight line graphs.

  2. resistivity if a nichrome wire

    Systematic errors. Calibration: calibration of all the equipment must be correctly carried out and made sure they are correct. For example, if the micrometer or the ruler was not calibrated correctly the readings taken may have been inaccurate; in future I will make certain that all equipment is correctly calibrated.

  1. The aim of this experiment is to investigate the relationship between the current, voltage ...

    This also confirms my hypotheses as being correct. > When current is passed through a filament lamp the resistance would increase in an irregular fashion. > So that a curved graph would be produced due to temperature increases. Results for both resistors were as expected based on scientific knowledge of

  2. Investigating electric potential between two parallel plates and around a charged sphere using a ...

    Electric potential kV/V 3.5 3.2 2.9 2.6 2.2 1.9 1.7 1.65 1.55 1.5 1.4 1.25 1.1 Distance from the centre of sphere d/m 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 1 Distance from earthed plate d/m-1 20.0 16.7 14.3 12.5 11.1 10.0 9.10 8.33

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work