• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Resistance Lab. Aim - To investigate the effective resistance (total resistance) of three resistors connected in a series circuit.

Extracts from this document...

Introduction

Physics

Lab Report – Resistors in Series

  • Aim - To investigate the effective resistance (total resistance) of three resistors connected in a series circuit.
  • Background – A resistor is an electrical component which opposes the flow of current in a circuit. When a resistor is connected in a circuit it produces a voltage across its terminals (measured using a voltmeter) using this voltage and the current (measured using a milliammeter) flowing through the circuit the resistance of the resistor can be calculated. Thus Resistance = Voltage/Current, this formula has basically been derived from Ohm’s Law which states that Voltage = Current * Resistance. In this experiment we have connected three resistors with unknown resistances in series circuit, the voltage of each resistor was measured using a separate voltmeter while another one was used to measure the combined overall voltage of all three resistors, further by using the above formula we can find the individual resistance of each resistor which can be added to give the effective (total) resistance of the three resistors connected in series. This was the first process used to find the effective resistance, the second process involved using the same formula only this time the total voltage across all the three resistors was used along with the current to directly find the effective (total) resistance of the three resistors connected in series. Both the above processes were repeated with a different value of current so that an average of the effective (total) resistance of the three resistors connected in series could be calculated for each process. Thus in this way the effective resistance of three resistors connected in series was calculated and verified using two separate processes.
  • Method -    
  • Variables –

1) Controlled – The entire set of apparatus.

2) Independent – The current used.

3) Dependent – Voltage across each resistor (individual resistance) along with combined voltage of the circuit (effective resistance).

  • Apparatus – A power pack, 4 voltmeters, a milliammeter, 3 resistors and connecting wire (with crocodile clips).    
  • Diagram -  
  • Method (contd.) -    
  • Procedure –
  1. First set up the circuit shown above. In order to this connect the power pack, the ammeter and the 3 resistors in a series circuit using some connecting wire. Then connect three voltmeters across each of the three resistors and then finally connect the 4th voltmeter (Vs) across all three resistors and all three voltmeters (as shown above).
  2. Now set the current in the circuit to 150 milliamps using the power pack and the ammeter.
  3. Quickly take the readings for the voltage across each individual resistor (V1, V2 and V3) and the combined voltage across all three resistors (Vs).
  4. Now repeat the above step until you get 4 sets of readings for each value of the different voltages.
  5. Next repeat the entire above procedure using a different value of current (200 milliamps)
  6.  Now for each value of current separately calculate an average value of the voltages on V1, V2, V3 andVs.
  7. Usingthe average values of V1, V2, V3 and the value of the current calculatethe values of resistance (R1, R2 and R3) for the three resistors, with both values of current, respectively.
  8. Now add the individual values of resistance (R1, R2 and R3) for the three resistors, with both values of current, to get the value of the effective resistance.
  9. Usingthe respective value of Vs and the value of the current in both cases, calculatethe value of the effective resistance (Rs) for the entire circuit and cross check with your above answer.
  • Results –
  • Raw Data Table –
...read more.

Middle

Trial 1

Trial 2

Trial 3

Trial 4

Trial 1

Trial 2

Trial 3

Trial 4

V1 (volts)

1.2

1.4

1.3

1.2

1.8

1.6

1.7

1.8

V2 (volts)

1

0.9

0.8

0.9

1.2

1.4

1.3

1.2

V3 (volts)

3.7

3.5

3.9

3.6

5

5.1

4.8

5.1

Vs (volts)

6

6.2

5.9

6

8

8.2

8.1

8

  • Processed Data Table –

Processed Data Table showing all the values used to calculate the effective resistance of all the three resistors by both processes for both values of current along with the overall average value of effective resistance.

Current = 0.15 amps

Current = 0.2 amps

Average value of V1 (volts)

(1.2 + 1.4 + 1.3 + 1.2)/4 = 1.275

(1.8 + 1.6 + 1.7 + 1.8)/4 = 1.675

...read more.

Conclusion

I made sure that the wires would not heat up too much by keeping the circuit switched off as much as possible.I took four trials of each voltage reading for both sets of to get a more accurate average set of results.
  1. Safe Test –

In order to conduct the experiment safely, I took the following measures.

  • I handled all the apparatus carefully so that no one was hurt and so that no apparatus was damaged, the resistors were handled with special care.
  • The circuit was always kept off when not in use.
  • The work space around me was clear so that there were no accidents and so that the experimental setup was intact.
  • Evaluation –
  1. Factors that could have led to experimental inaccuracies–

The factors, which could have affected the experiment negatively thus causing any experimental inaccuracies, are given below.

  • A slight error while measuring the volatges could have led to anomalies.
  • The current flowing through the circuit could have been slightly more or less than required, thus leading to inaccurate results.
  • While keeping the circuit on for too long the wire could have heated up thus affecting the resistances in the circuit.

...read more.

This student written piece of work is one of many that can be found in our International Baccalaureate 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 International Baccalaureate Physics essays

  1. Marked by a teacher

    Experiment to calculate the diameter of a piece of nichrome wire from its electrical ...

    3 star(s)

    Average trendline of Length vs. Resistance: Graph 2. Maximum and Minimum trendline of Length vs. Resistance: [KD4] More sample calculations: Sample calculation 4. Calculating the percent uncertainty of the average gradient: Sample calculation 5. Calculating the diameter Conclusion: From the graphs 1 and 2 above, it is evident that the

  2. IB Specific Heat Capacity Lab

    (6) - (7) (see data table) (T3 - T2) = 78.50 - 26.50 = 52.00 oC � (0.25 + 0.25) = � 0.50 oC = (0.50 � 52.00) � 100 = 0.96 % Heat absorbed by water (Hw) MW � CW � ?T = 61.47 � 4.18 � 4.50 = 1156.25 J = (0.03 + 11.11)%

  1. IB Physics Lab - Resistance

    * I also believe that when more resistors are added in a circuit, either series or parallel, the percent error will increase. Materials * Resistors * Breadboard * Multimeter Procedure 1. First, we obtained several different resistors, a breadboard, and a multimeter.

  2. Investigating Wires

    Time (s) Controlled Electricity was allowed to flow through each length of wire for the same period of time (time intervals had difference of 30s). This was because if electricity flows through a wire for a long period of time, it may cause the wire to overheat, and this changes the resistance.

  1. Factors affecting an electromagnet

    wire makes on the nail, and the value of the current running through the wire increases, then obviously the value of the magnetic field will also increase. Due to the fact that they are both directly proportional strengthen this case.

  2. HL Physics Revision Notes

    frequency, and length of exposure. Topic 13: Quantum Physics and Nuclear Physics: The photoelectric effect is the phenomenon where electrons are emitted from the surface of a metal after being exposed to light (of a particular frequency called the threshold frequency). Light below the threshold frequency will not cause electrons to be emitted.

  1. How does the sinkage depth of a tyre affect its rolling resistance ?

    1891) Rolling resistance is the force that resists the rolling of a wheel or other circular object along a surface caused by deformations in the object and/or surface. Generally the force of rolling resistance is less than that associated with kinetic friction.

  2. Experiment to show the application of Kirchhoffs Voltage Law & Kirchhoffs Current Law in ...

    I3 are all positive in value and the 2 currents leaving the node, I4 and I5 are negative in value. Then this means we can also rewrite the equation as: I1 + I2 + I3 - I4 - I5 = 0 ________________ Kirchoff?s second law that is KVL states that

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