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

    5. Record the values in a table. 6. Repeat steps 2 to 5, except with 2 x 1 x 1 cm, 3 x 1 x 1 cm, 4 x 1 x 1 cm, and 5 x 1 x 1 cm slices of apple. Experiment data Length of apple slice against its resistance Length (� 0.05 x 10-2 m)

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

    The next assumption is that the friction is evenly distributed over the whole sand paper. If we do not assume that, the frictional force acted on the blocks will be different all the times. The coefficient of the static and kinetic friction will also be different over the whole sand paper.

  1. Circuits - To prove the equation: Resistance (Ω) = Potential Difference Current.

    � (2.55 - 1) (0.06 � 1.55) 0.0387 Bulb 3 Gradient (y2 - y1) � (x2 - x1) (0.155 - 0.15) � (2.0 - 1.675) (0.005 - 0.325) -0.3200 Analysis From looking at my results and calculating the gradient for the graph I am able to see that as the number of bulbs in my circuit increased

  2. Find The Internal Resistance Of A Power Supply

    were not very reliable because the current increases and voltage decreases were fairly large that an accurate graph of current against voltage could not be plotted. Only four current and voltage reading were taken at each voltage setting on the power supply which meant that a small range of results could be plotted on a graph.

  1. Coursework To Find The Internal Resistance Of A PowerSupply

    This will ensure that the temperature of all the components will be kept constant and that no temperature change can occur. The connection between components can affect both ammeter and voltmeter reading significantly as I learnt from my preliminary experiment; a small gap between contacts can result in a large

  2. To Investigate How the Resistance of the Light Dependent Resistor Depends On the Current ...

    And the voltage in the circuit is equal toV2 plus the voltage of R2. The Voltage in the circuit keeps the same and the voltage of R2 increases, so V2 decreases. 2. I predict that the graph of the resistance of the LDR against to the current of the light

  1. Observe and record the brightness, voltage difference (the potential difference between two points in ...

    Procedure Testing the Current 1. Form a circuit as shown in Circuit 1 on the sheet attached. The battery must be set at 6V. 2. As shown with the letters, insert the ammeter. 3. Record the results. 4. Repeat steps 1-3 for Circuit 2, 3, and 4.

  2. Find the relationship between the current through a resistor and the voltage across it.

    In 1826, George Ohm had conducted several experiments with different metal wires to discover how the current through each depended on the voltage applied across its ends. Ohm's law states, "The current flowing through a metal conductor is directly proportional to the p.d.

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