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
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
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
Power is the Rate of Change of Energy
There are two booklets available on physbang.com to help you revise the equations that you are expected to know by the end of Y10. These booklets were posted a few months ago (click here to read that post and download the booklets) but it has since been pointed out that one equation is missing: sorry … Continue reading Power is the Rate of Change of Energy
SP8-9 Forces Doing Work (mini-test)
The first module of Y11 is now complete and to help you prepare for the assessment I have created a mini-test, complete with mark scheme and explanation. You can access the test by clicking here and the mark scheme is here. Work through the questions then check your answers to spot any errors or misconceptions … Continue reading SP8-9 Forces Doing Work (mini-test)
Voltage and Current
When you first started learning about circuits, either in primary school or in Y7, you should have been told about voltage and current. These two measurements were probably presented as separate ideas but in fact they both relate to one thing; electrical charge. Voltage relates to the amount of energy given to the charge that … Continue reading Voltage and Current
Energy is not Power!
Suppose that two identical twins decide to go upstairs in their house: one twin runs up the stairs whereas the other twin walks up the stairs. Which twin transfers the greatest amount of energy? Almost everybody says the twin who runs transfers more energy because she goes faster. This is a common misconception. In fact, … Continue reading Energy is not Power!
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