Resistance is how hard it is to get a current through wire at a particular voltage (p. d). The equation for resistance is Resistance, R = p. d across the wire (v) Current through the wire (I) The four factors affecting resistance are the length of the wire, as the length increases the resistance increases. The diameter of the wire, as the diameter increases the resistance decreases. The substance of the wire, some metals are better conductors of electricity than others and as temperature increases the resistance increases.
The resistance increases as the wire increases because as the length increases there are more atoms for the electrons to pass through. The resistance decreases as the diameter of the wire increases because the atoms are more spaced out so the electrons can pass through the wire more easily. The resistance changes as the material changes because if a wire is a good conductor of electricity its atoms have electrons around them if it is a good conductor of electricity the electrons will break off very easily for example in copper.
As temperature increases the resistance increases because as the temperature increases the atoms move about more, creating more of a barrier for the current to get through. I am going to investigate the resistance as I change the length of the wire. My preliminary results: – These are my preliminary results for how the length of wire affects the resistance. Length of wire (cm) Voltage (V) Current (Amps) Resistance (Ohms) .
I can see from my preliminary results that as the length of the wire increases, the amount of current, which gets through decreases, which means that the resistance increases. I can also see from my results that when the length of the wire has doubled the amount of current has almost halved. These are my preliminary results for how the thickness of the wire affects the resistance. Thickness of material Voltage Current (Amps) Resistance (Ohms) .
I can see from these results that as the thickness of the wire increases the resistance increases because the number of particles that the current has to pass through increases, creating more resistance. Prediction: – From my preliminary results I predict that as the length of wire increases the resistance will increase because when you increase the length of the wire there is more atoms for the current to pass through there for there is more resistance. I also think that when the length of wire has doubled the amount of current that gets through will have halved, I think this because it is shown in my preliminary results.
Apparatus: – Multimeter (measures resistance to 2 d. p) Micrometer (measures c. s. a) Nichrome wire (26 swg) Crocodile clips Battery pack Wire Method: – First of all I will measure out 5 lengths of wire, 30cm, 40cm, 50cm, 60cm and 70cm. I will do this by using a metre ruler. I will take 1 metre of wire to start with and measure the lengths of wire. I will cello tape the wire to the ruler to make sure that it is straight and that I’m getting the right amount of wire. I will then use a micrometer to make sure the wire is 26 swg. I will then set up my circuit and first put in 30 cm of wire to the circuit.