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

To investigate the relationship between the power consumed by a torch bulb and the resistance, by measuring the potential difference across the bulb and its current.

Extracts from this document...

Introduction

Name: Fawwaaz Hosein

Group Members: Eric Mui and Idris Khan

Experiment 2: Electrical Power

Date: 26th February 2010

Aim: To investigate the relationship between the power consumed by a torch bulb and the resistance, by measuring the potential difference across the bulb and its current.

Equipment:

  • Four (1.5V) batteries
  • Two multi-meters
  • Connecting wires
  • Rheostat
  • Switch
  • Torch bulb

Method

  • The equipment is set up as shown in the diagram (1.0) below.
  • One of multi-meters is used as an ammeter and is connected in series so as to measure the current (I) of the circuit and the other is used as a voltmeter connected in parallel with the bulb, to acquire the potential difference (V) across the bulb in question. The positive terminals of the multi-meters are connected so that they are facing the positive terminal of the batteries. The voltmeter is set to read volts and ammeter to read micro-amps.
  • The variable resistor (Rheostat) is adjusted until the current (I) observed on the ammeter is at its minimum value.
  • Readings are taken from each multi-meter. The ammeter gives the current (I) whilst the voltmeter gives the p.d across the bulb in question.
  • The variable resistor is adjusted so that the current (I) increases while the resistance (R) decreases. The readings of twelve (12) other points of equally spaced intervals are then taken so as to have thirteen (13) points in total. The values of V and I from the respective multi-meters are recorded and tabulated  
  • The relationship between the Power (P) and resistance(R), is determined using the equation stated below:

image00.png

                                                        P=kRn

                             Where P = IV, R = image02.png and k and n are constants.

  • In order to obtain a straight line graph to graphically represent the relationship between P and R, the following equation is derived:
...read more.

Middle

0.09

57.2

1.0

4.69

0.09

57.7

1.0

4.75

0.10

58.0

1.0

4.81

0.10

58.4

1.0

4.86

0.10

58.8

1.0

4.93

0.10

59.2

1.0

4.96

0.10

59.5

1.0

P% = V% + I% = ± 4%

R% = V% + I% = ± 4%

P (W)

P (W)

R (Ω)

R (Ω)

lnP

lnR

0.237

0.009

78.4

3

-1.44

4.36

0.240

0.010

78.6

3

-1.43

4.36

0.243

0.010

78.9

3

-1.41

4.37

0.247

0.010

79.4

3

...read more.

Conclusion

Conclusion:

From the experiment we concluded the following:

  • P=1.04 x 10-7  × R3.3559
  • n = 3.3559  
  • k = 1.04 x 10-7  WΩ−3.3559

To reduce the uncertainties of power and resistance, the uncertainties of voltage and current must first be reduces as they are linked. To achieve this V should have been measured more than twice at each current level. The number of current and voltage values should also be increased so as to have more values to plot on the graph. The power law in particular the formula used applies to this experiment, as lnP increases, lnR increases linearly; P is increased by the product of k and R to the power of n. This is also shown by the strong positive correlation of the graph that further shows that the power law is applied as when lnR increases, lnP increases proportionally or linearly.

...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. To investigate the relationship between current and potential difference (ohm’s law).

    Voltage measures the amount of energy used in getting each coulomb of charge through the wire. The units of volts are the same as joules per coulomb.

  2. Find The Internal Resistance Of A Power Supply

    I will now use a shorter rheostat so to give me a greater change in current as the bow connector is moved along the metal rail slightly. I am also going to increase the range of the results gathered and I will record the voltage and current readings at eight

  1. Investigating the Resistance Of A Light Bulb As The Voltage Is Increased.

    So therefore if ohms law is kept, the relationship between Voltage, Current and Resistance is that R=V/I, V=IR and I=V/R. The factors that can affect the resistance of a piece of wire are the thicknesses i.e. thicker wire the lower the resistance, as the electron flow has a larger volume to travel through than with a thin wire.

  2. The aim of the experiment is to verify the maximum power theorem and investigate ...

    So the numbers of pulling process should be minimized. On top of the above precautions, the spring balance is not connected to the wooden block firmly; it may be disconnected during the pulling process. Therefore, we should pay attention to the connection point between the spring balance and the wooden block during the experiment.

  1. Coursework To Find The Internal Resistance Of A PowerSupply

    I decided not to change the resistance setting on the rheostat while the power pack is continuously running but in order to maintain the same, constant, temperature of the power pack, it will be switched on to take the results and then switched off.

  2. To find which of the circuits, shown below, are most suitable to measure a ...

    = 1 x 10-4 Resistance of R1 = 50000? Pd across Resistor from Ohms Law V = IR V = 50000? x (1 x 10-4) V = 5V Current in V (I2) - Using the Pd for the circuit calculated above and the resistance reading specified form the voltmeter readings.

  1. Investigating The Characteristics Of A Light Bulb.

    I will go from 0.50 amps to 1.70 amps. I found that when I turned the power supply to 9 volts, the results were the best. On the graph, the line was bent, which means that the voltage increased. Experiment we used a 3-1/2 volt bulb and 4 was the maximum voltage we could use on the power supply.

  2. Investigation On The Resistivity Of Apples. Since we are measuring the resistance of an ...

    Using the multimeter, we measured its resistance during class. Data: Length (� 0.05 x 10-2 m) Sample Resistance (�0.05 x 103 ?) Trial 1 Trial 2 Trial 3 Total Average 1 1 263.0 200.0 160.0 158.1 � 104.9 2 125.5 127.7 117.0 3 135.0 140.0 155.0 2 1 266.0 210.0

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