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Investigation between resistance of wire and length watch

    • Thread Starter

    i am doing some coursework at the moment, it is an investigation of the relationship between the resistance of a wire and its length.
    Please post some info as i dislike physics :confused:

    Ok there is probably alot about this elsewhere on the internet, but basically, double length, double resistance. Also resistance = (resistivity*lenght)/cross-sectional area

    Dont confuse Resistivity with Resistance. They are not the same.

    You will probably need an volt-meter, ammeter, power supply, ruler for your investigation. (Which could all be replaced by a digital multi-tester that can measure resistance directly)

    Also V=IR might be used if you have to use volt-meter ammerter to work out resistance.

    Take different lengths of wire (making sure everything else is the same - same sort of wire - same cross-sectional area). Measure the resistance for different lengths.

    You can then plot a graph of your results. What type of graph you get will reveal the relationship. (straight-line graph, straight-line through origin, exponential etc).

    Try to plot more than 6 points.

    Are you being provided with wire which has a known resistivity?

    If not, what will you be using?

    The things you will need to consider are:

    What will you use for a power source?

    How will you secure the wire to the power source?

    How will you access the circuit to measure voltage?

    How will you access the circuit to measure current?

    What precautions will you take to ensure a) you don't burn yourself and b) you don't set fire to something? (this becomes important if a high current results from the way you connect the wire to a power source)

    Are you doing this in class or at home?

    Sorry if all the above sounds a bit thick - but I am a parent (and used to do daft things with electricity as a boy!!!)

    Be careful (in an academic sense) if you choose to use a multimeter to measure the resistance of the wire directly using the ohms range. Most "domestic" multimeters I've come across don't have the ability to "zero" the ohms range when touching the probes together. That usually means there will be a built-in error. It's far more reliable to use the votage and current measurement and then do the sums.

    Does that help, or just confuse?


    the longer the wire the more resistance...the thinner the wire the more the resistance
    just explain what resistance is ( ref to electrons) and use the relationships above

    u can also u different types of wires
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