Safety:
Do not turn the ammeter above 0.25 to prevent a fire or the burning of the wire. When conducting the experiment don’t touch the wire as it will be hot. After the experiment let the wire cool down as it will have some of it’s heat from before hand. The experiment should not be dangerous at all as long as the current stays below the 0.25.
Apparatus:
An ammeter, instrument used to measure the magnitude of an electric current of several amperes or more. An ammeter is usually combined with a voltmeter and an ohmmeter in a multipurpose instrument.
Voltmeter:
voltmeter is an instrument used to measure differences of electric , commonly called voltage, in volts or units that are multiples or fractions of volts.
Crocodile clips: These are used to connect all the appliances together and to also allow current to flow through them.
Metre rule: Used to measure how much wire we are using.
Wire: We are using this strip of wire to test the resistance of it.
What is the Circuit for?
Circuit
A circuit is a path for electrons to flow through. The path is from a power sources negative terminal, through the various components and on to the positive terminal.
Think of it as a circle. The paths may split off here and there but they always form a line from the negative to positive.
Some variables that will be relevant to this investigation are:
- Length
- Thickness
- Temperature
- Voltage
- Resistance
- Material
The thinner the wire is the less channels of electrons in the wire for current to flow, so the energy is not spread out as much, so the resistance will be higher: We see that if the area of the wire doubles, so does the number of possible routes for the current to flow down, therefore the energy is twice as spread out, so resistance might halve. The resistance of a wire is directly proportional to the length and inversely proportional to the Area. Hence doubling the length of a wire increases the resistance by a factor of two, doubling the area would decrease the resistance by half. The proportionality constant relating resistance to the length and area of a wire is the resistivity of the wire. Resistance=Resistivity x length/area
Ohms Law
“The amount of current flowing in a circuit made up of pure resistances is directly proportional to the electromotive forces impressed on the circuit and inversely proportional to the total resistance of the circuit.”
(Voltage ÷ Current = Resistance)
Conclusion
I came to a conclusion that the decrease in current is the increase in resistance this is because the current although less of it they collide with the resistance causing a decrease in the output voltage.
Evaluation:
The experiment proved to be a success and it went very well although it could be improved by trying other lengths, different voltages but also a different type of wire to be able to compare the resistance difference this would make a more interesting experiment
