The investigation I did was to find the resistance of a piece if wire. The piece of wire is my dependent variable throughout the investigation. I changed the length of the wire in order to measure the resistance of each length. Plan
In this investigation, a simple circuit will be set up to read the voltage and current when the length of the wire changes. The length will range from 10cm-80cm with intervals of 10cm. The length of the wire will be changed by moving the crocodile clip across the wire and checking the measurements with a ruler. The circuit should be set up as in the circuit diagram (as attached). The voltmeter should be set up parallel to the ammeter. The readings from the ammeter and voltmeter will be used to work out the resistance. This can be done using the formula: R = V/I (V is the potential difference in volts, I is the current in amperes (amps), R is the resistance in ohms, Ω) Safety
In order to perform a safe experiment, a low voltage of 4v was chosen so that it won’t over heat and to avoid electrocution. The power pack must be turn off between readings/ when moving the wire. If the wire gets hot or if there’s a smell, the plug should be turned off immediately. Fair test
To ensure that the investigation is carried out in fair way, the wire must be measured as accurately as possible and the same circuit and power supply must be used throughout as different power supplies may have different voltages. The experiment will be repeated three times for each length of wire, with low, medium and high resistor. Also, an average should be taken to enable that the test results are reliable. Apparatus used
* 2 crocodile clips
* Power pack
* 6 wire
* A meter ruler with attached wire
* A variable resistor
* A calculator
1. We set up the circuit as drawn on the circuit diagram.
2. Then starting with 10cm, we measured the wire with the metre stick and place the crocodile clips at the...