Resistance of a Wire
Planning:
I am going to design an experiment to measure how the length of the
wire affect the resistance in the wire. I will use the same wire for
all my measurements. It is important to have a fair test, so the
cross-sectional area of the wire must be the same for all measurements
because as the cross-sectional area increase the resistance decrease.
It is also important to have the wire made of the same material
because different materials have different resistance, nichrome is the
good conductor of electricity .The temperature also affect the
resistance because when it increase the resistance in the wire
increase. To get the correct and accurate measurements it is important
to keep all the factors that affect the resistance the same and only
vary the length.
Predicting:
The longer a wire, the greater its resistance. This is because the
charges have further to go through the material; there is more chance
of collisions with the atoms of the material
Selecting the most suitable apparatus:
For my experiment I will use metre rule, ammeter, voltmeter, battery
and copper wire. metre rule: I will use it to measure the length of
the copper wire Ammeter: I will use it to measure the size of a
current flowing through the wire. The electric current flowing through
the circuit is measured in amperes or amps. It does not matter where
to put the ammeter in the circuit because the current is the same
everywhere. The ammeter has to be connected in series, it is important
to connect an ammeter so that its red (+) terminal is always nearer to
the positive pole of the cell than to the negative pole. Voltmeter: Is
used to measure the potential difference (p.d.) it is measured in
volts (V). The voltmeter must be connected in parallel, across a
component (nichrome wire). As with an ammeter, the voltmeter must be
connected the correct way round (positive to positive). To get accrued
readings I will have to use digital ammeter and voltmeter.
The individual will have their blood pressure levels taken using a blood pressure machine called a sphygmomanometer, where a cuff is placed around the individual’s arm and fills up with air to create pressure around the arm to restrict the amount of blood flow and takes a pulse reading as it releases the pressure. After the individual’s blood pressure has been taken they may be asked to take it at home using a blood pressure kit to see if it is still high and that the first reading was not due to anxiety.
1. Decide on a range of temperatures from 5 °C to 35 °C to be tested.
- The area should be kept dry and taps should be switched off. Variables: I will only be changing the current by moving the variable resistor. I will repeat the experiment twice so that I can be sure of my readings and see if anything has changed or gone wrong. I will take 12 readings at 0.1 amps intervals. Apparatus: o Voltmeter o Ammeter o Variable resistor o 12 volt lamp o Battery pack (set at 12 volts ) o Leads Method: 1.
Volume's Effect on a Copper Sulphate Solution We are trying to find out if the current though a copper sulphate solutions volume is increased. To find this information out I shall perform an experiment using the following equipment; · 1 power pack · 1 beaker · 2 carbon rods for anode and cathode · 1 ammeter · 1 measuring cylinder · 2 crocodile clip wirers I shall also be using 60cm3 volume of copper sulphate in my preliminary results to decide upon the concentration of copper sulphate and the voltage I shall use. The following diagrams show the step by step process in which I will do my experiment; [IMAGE] [IMAGE] [IMAGE] [IMAGE] I will take 10 readings from 10cm3 to 100cm3. I will repeat my experiment to give my experiment a fair average. I will keep the power pack the beaker the carbon rods the crocodile clips the ammeter the concentration of copper sulphate and the measuring cylinder the same each time I do the experiment this experiment.
Procedure: In order to find the specific heat of copper and the percent error of the calculations make the first step that need to be taken is to measure the mass of the copper. The mass needs to be between 25-30 grams of copper and put into a test tube. After finding the mass of the copper place two test tube holders on the test tube and suspend the copper filled test tube into a hot water bath provided by teacher. While the metal is heating, look up the real specific heat of copper and construct a double cup calorimeter. Add 100.0 ml of water to the calorimeter and take the temperature of the water. The temperature should be around 20.0-25.0° C. After the copper filled test tube has been in the hot water bath for ten minutes, put the hot copper into the calorimeter, put the lid on the calorimeter, stir the water with copper in it and take the highest temperature that the copper/water mix reaches. After taking the temperature separate the water from the copper and return the copper to the correct container. To find the specific heat divide the heat transferred by the mass times the temperature change (Cp=Q/m x ΔT). To find the percent error, the actual specific heat of copper need to be subtracted from the specific heat found, be divided by the actual specific heat time 100. Repeat this experiment two more times , changing the mass of the copper or the time you heated it.
Whilst doing the experiment there are many things that will have to remain the same in order to keep the tests fair, these include amounts and measurements as well as concentration and size and shape of the magnesium e.g. long strands. The temperature how ever will be the main change in the experiment, this is the only factor to change in less problems occur where a change is not optional. For each temperature the test will be taken three times to make sure that the results are correct and as accurate as possible, an average will be taken to give a clear and single result. A diagram of the apparatus I intend on using and how it will be assembled; [IMAGE] Safety- To ensure that the investigation is safe I will make sure that all equipment it correctly assembled, and I am wearing the appropriate safety wear and that everybody around is either dressed correctly or far enough away.
Measuring the Resistivity of a Wire Aim The aim of this experiment is to find out how the area of the cross section of the wire affects the resistance and also to find out the resistivity of the wire having found the resistance over a certain length and using a certain cross sectional area. I will also experiment to see how the length of the wire affects the resistance. Plan The first thing that I will do is to set up the apparatus as shown. below. The.. A, V Except for the experiment where I alter the length, I will keep the length of the wire constant throughout the experiments and only change.
have to be across the wire and not just anywhere in the circuit so it
I also decided to use a wooden block to keep hold of the wire, because
F Another wire, or exact same properties (Nickel Chrome, thickness 34). mm and length 30cm) was placed on top of the previous wire, in the same position, both straight and flat. F. The power was turned on again and the same procedure was repeated. recording current and voltage at three points on the variable. resistor.
This is know as resistivity. The factors I can investigate are : Ÿ Temperature Ÿ Length Ÿ Cross-sectional area/width Ÿ Material (resistivity) The factor I shall investigate is the length of a wire. Background Knowledge Resistance is when electrons travelling through the wire are impeded by the atoms within the wire. Since the electrons are charge carriers when they collide with the atoms in the wire less pass through.
-Voltmeter -Variable resistor -Power Supply -Various diameters of wire -Crocodile clips -Metre ruler [ IMAGE] Diagram:.. Secondary Source - (Obtained in A-level PHYSICS by Roger Muncaster). Page 536 - "The 'Page The electrical resistivity of a material is defined by R = L / A Where R = Resistance of some conductor(Î).
Copper wire, bare, 24-gauge, 9 V battery, 9 V battery clip, and more. I am going test each liquid to see which liquid has more electrolytes, and by knowing that it will help me find out which is better for you. I believe by doing this experiment it will help me see if my hypothesis is right or
You take voltage measurements by counting the number of divisions a waveform spans on the oscilloscope's vertical scale. Adjusting the signal to cover most of the screen vertically, then taking the measurement along the centre vertical graticule line having the smaller divisions makes for the best voltage measurements. The more screen area you use, the more accurately you can read from the screen.
Ohm’s Law is also subject to a specific amount of pressure on the substance. For example placing a conductor under tension (a form of strain), causes the length of the section of conductor under tension to increase causing the cross-sectional area to decrease, hence changing the value of resistivity and conductivity.