When carrying out a practical investigation it is always helpful to know what sorts of results are expected. In other words, before starting an experiment it is a good idea to consider what theory tells us should be the outcome. The predicted findings form the basis of an hypothesis, which is developed by considering an … Continue reading Hypothesis and Analysis
Key Facts: Electric circuits
Electricity is one of the forms of energy transfer so it is not surprising that the definition of the volt (the unit for measuring potential difference) is the energy carried per unit charge. In symbols, where Q is the symbol for charge, this relationship is written as; V = E / Q It is important … Continue reading Key Facts: Electric circuits
Investigating I-V Characteristics
Many GCSE Physics courses, including AQA Trilogy, include a compulsory practical to investigate the current-voltage (I-V) characteristics of various electrical components. This experiment links back to the work done by Georg Ohm, whose results have previously been summarised as; "the current flowing through a conductor is directly proportional to the potential difference (voltage) across the … Continue reading Investigating I-V Characteristics
Ohm’s Law
Potential difference (voltage) and current are fundamental measurements for electric circuits. Multiply the potential difference across a device by the current flowing through it to get the power rating for that device.Multiply the power rating by the time for which the device is used to get the energy that the device has transferred. All of … Continue reading Ohm’s Law
Energy Transfers in Electric Circuits
The amount of energy transferred in an electric circuit can be calculated by multiplying the current, time and potential difference. This is expressed in the equation given below. Current is measured in amps (amperes), time is in seconds, and potential difference in volts. Remember that the symbol for current is the letter I - not … Continue reading Energy Transfers in Electric Circuits
Resistance theory
Often it is true in physics that if you can understand one thing then it will automatically help you to understand something else. A good example of this occurs in resistance, where the model of resistance in a wire links directly to the behaviour of circuits that have resistors arranged either in series or in … Continue reading Resistance theory
Transformers
The famous "electricity war" between Edison and Tesla wasn't just about electricity generation, it was also about electricity distribution. Edison's DC electricity couldn't be sent very far due to power losses but Tesla's AC could go much further and benefit people over a much wider area. Efficient electricity distribution relies on minimising power loses due … Continue reading Transformers
Electricity and Magnetism
Whenever a current flows through a wire, it creates its own magnetic field. This may be surprising given that copper, which is normally used for electric wires, is not a magnetic material, but it is true nevertheless. This fact was discovered almost exactly 200 years ago by the Danish physicist, Hans Christian Oersted and led … Continue reading Electricity and Magnetism
Correct wiring of a 3-pin plug
There once was a time when the ability to wire a 3-pin plug was an essential skill - but not any more. For reasons of safety, many devices are now fitted with molded plugs that cannot be opened or removed. Nevertheless, the exam board still expects you to be able to identify the essential features … Continue reading Correct wiring of a 3-pin plug
DC and AC Electricity Pt1: Electron Movement
One of the most famous technological "wars" was the battle that raged almost 150 years ago between Thomas Edison's DC electricity and Nikola Tesla's AC electricity. For our purposes, we will put aside the stories of the two men (Edison was an inventor and businessman whereas Tesla was a scientist and idealist) and focus on … Continue reading DC and AC Electricity Pt1: Electron Movement
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