Introduction In this piece of coursework I aim to find the effects of length on a piece of nichrome wire. Resistance is a force which opposes the flow of an electrical current, this is why energy is needed to push the particles around. The circuit also contains its own resistance if the wires vary in thickness, a thin wire has a high resistance as there is less room for the particles to move and a thick wire has a low resistance because the particles can move around very easily.
It’s also measured in ohms. George Ohm discovered that the emf (Electro motive force) is directly proportional to the current, this means if you double one you double the other. He called this resistance; the formula for working it out is as follows- Resistance = Volts Current Prediction I predict that as the length increases the resistance will also increase in proportion to the length, my graph should also show that they are proportional this is from my scientific knowledge that says.
– Nichrome wire conducts electricity very well and because current is the movement of atoms through the wire, if the wires length is doubled so is the number of electrons which will double the resistance. Predicted graph- How am I going to do it? Materials 1. Power pack 2. Rheostat 3. Volt meter 4. Ammeter 5. Nichrome wire 6. Wires 7. Crocodile clips 8. Sellotape The wire was sellotaped to a metre rule with excess at both ends for the crocodile clips to be attached. The rest of the equipment was assembled as shown in the diagram below.
I chose to take the readings in ten 10cm gaps. I placed a crocodile clip at each measurement and record the resistance three times for an accurate average and then put the averages on a graph. Circuit diagram Results table To make sure of a fair test I am going to do the test 3 times and then plot a mean on a graph. Length Pd(v) Current (I) Resistance(V/A) 3 Length Pd(v) Current (I) Resistance.
From all these results a mean was worked out. Length Resistance What do they mean? Without a graph its hard to tell below is a graph of the results Conclusion The graph is a straight line and passes through the origin, this indicates that resistance is directly proportional to length. This means that if the length is doubled then so is the resistance Evaluation From my graph I can see that my results that I collected are very reliable.
I know this because my graph does not show any anomalies, this is because the graph is a straight line with no bulges or severe direction changes. There are several changes I could make to ensure better results were gained. – When I was measuring the lengths of wire, my measurements might have been inaccurate, as the rulers used might be slightly varied and not exact. It was difficult to get an accurate reading of length by eye, as the wire was not completely straight or flat, these could have caused slight variations in my results.
But not affected them too much. Other variables that could be changed are – * Temperature of the wire * Diameter of the wire Overall the experiment went well and my results were good, and clearly prove my hypothesis. 1 5 1 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.