We think of light as being special - but that's only because our eyes respond to it, allowing us to see the world around us. In fact, light is just one example of an electromagnetic wave. Other electromagnetic (EM for short) waves include infra-red, ultra-violet, radio and x-rays. The range of EM waves, known as … Continue reading Electromagnetic Waves (overview)
Microphones and Loudspeakers
There is a great cross-over between two topics, waves and electricity, when we come to moving-coil microphones and loudspeakers. This pair of devices can be thought of as the sound-wave equivalent of motors and generators. Motors turn electrical energy into kinetic energy whereas generators turn kinetic energy into electrical energy. Similarly, microphones turn sound waves … Continue reading Microphones and Loudspeakers
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
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
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
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
Quantum Game
If you want to play a fun game and (optionally) learn about the curious behaviour of light, then Quantum Game is for you! The nature of light has divided opinion in physics for literally thousands of years, from the time of Pythagoras and Aristotle in ancient Greece to the current day. In the seventeenth century, … Continue reading Quantum Game
Home Study Projects
Constantly going over things that you have already learned can get a bit boring so if you want to extend your knowledge over the summer holiday then it's a good idea to do so using some fresh material. Finding suitable resources can be tricky so let me suggest some materials that are provided online at … Continue reading Home Study Projects
Surface Colour and Cooling
In the same way that surface colour affects the rate at which objects heat-up and the maximum temperature that they reach (as discussed here) so too will the surface colour affect the rate of cooling. As before, there is a standard experiment that you are expected to know and a typical set of curves that … Continue reading Surface Colour and Cooling
Surface Colour and Heating
Most people say you shouldn't go out on a summer's day wearing black because you will get too hot. It would be much better to wear white as this will keep you cooler. But is that actually true? We can test this idea using two boiling tubes that have been sprayed to have different surface … Continue reading Surface Colour and Heating
Mr Tarrant's physbang 'blog 