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The factors affecting the current flow through a conductor at a constant temperature.

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Introduction

Brief

I need to investigate the factors affecting the current flow through a conductor at a constant temperature.

Introduction

Resistance is a force found in currents that opposes the flow of electrons around a circuit. When this occurs energy is needed to push the charged particles around the circuit. The circuit itself can resist the flow of particles if the wires are either very thin or very long. E.g. the filament across an electric bulb is quite thin as needs to resist the flow of particles for the bulb to glow. Resistance is measured in Ohm’s because George Ohm discovered it.

Plan

As I need to investigate the factors affecting current in a circuit I need to vary something connected to current. The ideal choice is Ohm’s law (resistance = voltage/Current) because voltage and resistance are easily changed to vary the current. Ohm’s law is sometimes written like this: V = Voltage

C = Current

R = Resistance

Current is the flow of electrons in a circuit. This is what an ammeter measures. There are 2 types of ammeter, digital and analogue. Digital readers are easier to read because the current is displayed as a number.

Middle

Reliability

I know that the results will be accurate because having a second experiment will check them. Any anomalous readings will hopefully be averaged out and will not have a significant impact on the final result.

Measurements

The measurements will be recorded in ohm’s, volts, and amp’s and also in degrees.

Proposed Range

I will hopefully get a range of 0-1 amps during the experiment.

Hypothesis

I predict that when the resistance in the circuit increases the current and the voltage will decrease, according to Ohm’s law (resistance = voltage/Current).

As the resistance increases there will be more ‘hurdles’ for the electrons to conquer as they travel around the circuit, and this is why the voltage and current will decrease. As long as the temperature remains constant this hypothesis will be accurate. The resistance will be proportional to the current.

Obtaining Evidence

Conclusion

If I had the chance to conduct an experiment like this again I would change the voltage as well whilst keeping the resistance and current the same to prove Ohm’s law correct. I would then be able to cross-reference the results and make a full investigation of the brief. The method for the next experiment is shown below.

1. Set up the circuit as shown in the original circuit diagram.
2.  Prepare a results table to record the data from the circuit. It should include voltage and resistance readings. The resistance will be calculated as before.
3. Instead of a variable resistor it may be a prudent decision to use a fixed resistor. The results will be taken more accurately and will keep it a fair test.
4. Repeat each part of the experiment twice, to gather average readings and to filter out any mistakes.
5. Draw a graph of the results to compare with the graph of current against voltage.
6. Draw another conclusion and evaluate the investigation, stating how it worked and what went wrong.

I would have also liked to make the recordings with an analogue reader to test the difference in accuracy between an analogue reader and a digital reader. This would have also been an interesting investigation.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

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