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
Under(water) Pressure
Pressure explains why an applied force makes a drawing pin goes into the noticeboard and not your thumb: it also explains why a sharp knife is safer than a blunt one when practising culinary skills. There is also another aspect of pressure that relates to forces within a fluid (liquid or gas) and that is … Continue reading Under(water) Pressure
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
Magnetic fields
Magnetism is a well known effect that was observed in nature thousands of years ago. In fact, the word "magnetic" comes from the region of Greece where materials that could attract and repel each other were first discovered: this region was called Magnesia. The knowledge you need to have about magnets is very straightforward but … Continue reading Magnetic fields
The Sand and the Swimming Pool
Here’s an interesting problem that is directly applicable to the behaviour of light. Suppose that you want to get from point A to point B, what is the fastest route? The most common answer is “in a straight line” but this isn’t always true. Let’s put our points A and B on a sandy beach … Continue reading The Sand and the Swimming Pool
Take part in Star Count 2021
Every year, in mid-February, people in the UK (including the Channel Islands) are invited to take part in the CPRE's annual Star Count. The purpose is to create a map that shows how dark are our skies, based on how many stars can be seen within the constellation of Orion. This year's event is live … Continue reading Take part in Star Count 2021
Compare and Contrast
A really useful revision tactic (and also quite a common type of exam question) involves looking at the differences that exist between two related things in the same area of physics. These comparisons can be very simple, such as the definitions of scalars and vectors, or they can be more complicated, such as competing theories … Continue reading Compare and Contrast
Electric fields
A field, in physics, is a region of space where one object can affect another object without the two objects touching each other. The most familiar fields are gravitational and magnetic but now we need to gain some understanding of electric fields and their shapes. Let's start with a quick recap of what we know … Continue reading Electric fields
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 Pt2: Seeing the Difference
We commonly use meters to make measurements in electric circuits but meters are relatively simple devices and if the property we are measuring changes over a short period of time then a meter will not show this clearly (if at all). But a different instrument, the oscilloscope, has the power to reveal such changes in … Continue reading DC and AC Electricity Pt2: Seeing the Difference
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