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
Magnificent moles
You may well ask, what is the point of an SI unit that measures “amount”? Surely if we want to know an amount then we simply count whatever it is that we need to quantify. That’s fine until we get to VERY large numbers. How large? We’re talking here about numbers that are massively bigger … Continue reading Magnificent moles
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
Online Circuit Simulators
One of the best ways to learn about circuits and resistance is by building circuits - either in the classroom or using an online simulation. I've previously recommended PhET DC Circuit simulation, which (despite some non-standard circuit symbols) is still a great way to take measurements that demonstrate concepts such as Ohm's Law. You can … Continue reading Online Circuit Simulators
Auto-electric?
We all know that fossil fuels are bad for the environment and that their use in cars is being phased out but how much do you know about the alternatives? Electric cars probably spring to mind but what about other options that might actually be better choices? This is relevant for the GCSE course and, … Continue reading Auto-electric?
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
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
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
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
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