• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14
  15. 15
    15
  16. 16
    16

What factors affect the size of an electric current?

Extracts from this document...

Introduction

image00.png

PROJECT QUESTION

What factors affect the size of an electric current?

Electric Current is the flow of charge through all states of matter. There are 5 factors that effects the size of an electric current. They are:

  • Potential Difference between ends (Voltage)
  • Temperature
  • Material of wire
  • Length of wire
  • Area of Cross- section

AIM

To investigate experimentally the effects of conducting wire length on the current.

Figure 1- Circuit Diagram of apparatus used in this investigation

image01.png

image07.pngimage07.pngimage17.pngimage22.pngimage19.pngimage07.png

image35.png

image07.pngimage19.png

image13.png

image01.png

KEY

image14.png

Low voltage variable DC Supply- Power supply by which the voltage

can be varied

image15.png

Voltmeter- measure potential difference (voltage) across wire

image16.png

Ammeter- measure current

image17.png

Varied Conducting Wire length

Constant Conducting Wire lengthimage18.png

SCIENTIFIC THEORY:

An electric current is the flow of electrons around a circuit through a conducting wire of metal. The wire is made up of positive ions, atoms that have lost electrons.

Figure 2- Cross- section of a wire

image21.pngimage20.pngimage21.pngimage20.pngimage20.pngimage20.pngimage21.pngimage21.png

image20.pngimage20.pngimage21.pngimage21.png

image21.pngimage21.pngimage20.pngimage20.pngimage20.pngimage20.pngimage20.pngimage20.pngimage21.png

image20.pngimage20.pngimage24.pngimage20.pngimage23.pngimage20.png

image25.png

When they have enough energy, the electrons in the outer shell of the atoms become free, leaving the atoms as positive ions. They get this energy from the power supply. The sea of free electrons flows past the ions as they gain more energy. However ions are obstacles and they often collide with the electrons, as there is not enough space. Each collision results in a loss of energy. The longer the wire the more atoms it contains.

...read more.

Middle

image39.pngimage37.pngimage38.pngimage36.pngimage36.pngimage33.pngimage34.pngimage34.pngimage34.pngimage39.png

image40.png

image41.png

image44.pngimage34.pngimage42.pngimage43.png

The thick membrane stops the negative and positive terminals attracting each other. In the right terminal of the battery the free electrons are repelled because it has a negative charge. The left terminal has a positive charge so it attracts the negative electrons. This gives the electrons in the current a direction to flow in.

PREDICTION:

I predict that the longer the conducting wire length, the smaller the current shall be (lower value in Amps). So if the wire length is doubled then the current shall be halved because the resistance increases (V= I x R)

I = k X1

          L

I α 1

      L

As the wire gets longer (and the temperature remains constant), the resistance shall increase proportionally.

The formula for resistivity is:

R =  pl

         A

R – Resistance

P – Rho- Resistivity of material

L – Length of Wire

A – Area of cross-section

 I  – Current

Using this formula:

When l=1 and A=1, R= p  

So when the length is doubled, the resisitivity is doubled as well:

When l= 2 and A=1, R=2 p.

This suggests that the length is proportional to the resistivity, and the resistance in a circuit is dependant upon the voltage and current

Figure 4- Graph showing that the increase in Current is proportional to the increase in Voltage. This is because the higher the electrical pressure the more electrons go around the circuit. Therefore the line showing resistance is straight and follows Ohms law

image45.png

image46.pngimage47.pngimage48.pngimage49.pngimage03.png

image02.png

image03.png

image04.png

image05.png

Ohm’s Law:

V = I x R

...read more.

Conclusion

  • A large range of data was collected
  • The surfaces of the contacts were cleaned before they were used so that there was a good connection.
  • Changes made to the method after the preliminary experiment were good, and made a difference as the experiment was a lot fairer and so the results of the main experiment were more accurate than the results of the preliminary work carried out.
  • The crocodile clip was attached to the wire the same way for each of the different wire lengths.
  • As a result of the preliminary we were more familiar with the experiment and so were able to complete the experiment comfortably in the time given without rushing.
  • Constantine wire was used which does not heat up as easily as other wires, and so temperature did not really affect my results

As an extension to this piece of work I could use other wires made from different material like Nichrome wire for example and investigate the pattern between the current and wire length using wires made from different materials. I could also use wires of different thicknesses and investigate how the current changes as the length does.

To further investigate factors that affect the size of an electric current I could look at experimentally, another factor that effects the current and compare my findings to this experiment. I think I would look at the cross-sectional area of the wire. It would provide me with more evidence about changing the size of an electric current.

...read more.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism 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 GCSE Electricity and Magnetism essays

  1. The Efficiency of an Electric Motor.

    meter and the energy it recorded and I will be able to draw a calibration curve. My Results: Load=10.3? Voltage (V) Time for 10J 1.97 20.9 1.8 22.9 1.6 26.7 1.4 33.4 1.2 46.7 1 69.5 0.8 112.68 0.5 360.76 0.4 593.72 * I would have repeated my results for

  2. To investigate the affect of wire width on electric current and resistance.

    Therefore, the colder something is, the less it's molecules move, and vice versa. This diagram demonstrates the kinetic theory in gases. [image003.gif] Relating to the theory of current flow and resistance, we see that as the temperature increases the atoms which the electrons flow past vibrate more.

  1. An experiment to find the resistivity of nichrome

    Resistance also depends on the material of the conductor. The resistance of a conductor, or circuit element, generally increases with increasing temperature. When cooled to extremely low temperatures, some conductors have zero resistance. Currents continue to flow in these substances, called superconductors, after removal of the applied electromotive force.

  2. Investigation of the factors that affect the resistance of a wire.

    and the average resistances obtained from the different wires will be plotted on a graph showing the resistances found against the different wires with different cross sectional areas used. OBSERVATION AND RESULTS: In order to fit all of my results into the following tables I have had to replace certain

  1. Investigate how resistance can affect the amount of current flow.

    Manganin 0.62 A 0.5 V 0.81 ? Constantan 0.56 A 0.5 V 0.89 ? Nichrome 0.25 A 0.5 V 2.00 ? Later on I selected copper and nichrome to work out which of them would be useful to find suitable material.

  2. To investigate the factors affecting current in a wire.

    But in practice, I had to change it to 4V and make sure the reading on the voltmeter was always constant at 2V. The voltage was kept constant by adjusting the rheostat (as explained earlier). I chose a low voltage so that less heat will be produced.

  1. Investigate the resistance of a wire at different stages on the power supply.

    The constantan wire is the same length throughout the experiment that I did. The measurement that I used was 26 SWG. 0.45 mm in thickness. With this I did my experiment. Method Firstly I got all my equipment out, and neatly placed it out making sure it wasn't in anyone's way.

  2. Planning Experimental Procedures

    And also changing one variable at a time will help me compare my data instead of having 2 variables different. I am going to control each of the variables. I will control variable one which is the material of wire by carefully reading the labels on the wires when choosing

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