How to measure a voltage?
To measure a voltage you have to use a voltmeter. When measuring the voltage you must connect the voltmeter across the lamp because this is what pushes the current through the lamp. To set it up you must have four wires connect one between the lamp and the voltmeter and another one on the other side then connect one on the top end of the battery and another one on the other end of the battery.
How to measure current?
Use an ammeter to measure current. You connect the wire to the lamp or whatever you are using and then connect it to the battery and then the switch or whatever you are using and also the ammeter. The current then flows through the lamp and then through to the ammeter which shall show a number on it which is the length of your current.
My Prediction
I think as you increase the length of the Constantan wire, you also increase the amount of resistance. The current is the flow of electrons; the current is dependent on the amount of voltage, which is applied. Voltage is the push given to the current. The current has to go through a circuit, which contains resistance so if you increase that push you also increase the flow of the current. All materials have a slight resistance to electricity factors affecting the resistance are: Length, Voltage & Temperature and Surface Area
Equipment:
- Stopwatch
- Power pack
- An ammeter capable of measuring up to 5a
- An voltmeter capable of measuring of up to 10v
- A metre ruler
- 2 crocodile clips
- 5 connecting Leads
- 2 Constantan wires 1m length
Method:
1. Arrange apparatus as shown in the Diagram:
2. Organize wires to the following lengths:
10cm
20cm
30cm
40cm
50cm
60cm
70cm
80cm
90cm
100cm
3. Attach the wire to the crocodile-clip leads and set voltage to 5 volts or 1.5 Volts
4. Take the reading from the ammeter and record in results table.
5. Repeat 3 times for each length of wire and find the average.
6. Then work out the resistance using the formula V÷I=R
(Voltage ÷ Current = Resistance)
Preliminary
We carried out a preliminary experiment to see the other factors that could affect the experiment and also to see if we could improve any of the steps in the method. This showed that the wire was very weak if given more than 5 volts because the wire lets electricity flow faster and faster which then leads to the heat eventually breaking the wire. I found that if I decreased the voltage to a reading of 1.5 volts the wire stayed in tact enough to give a good reading and thereby giving better overall results.