G482 OCR Physics A Revision Notes - Unit 1 (Electric Current)

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Electric current is the net flow of charged particles. These charged particles are electrons when they are in a metal, and ions when in an electrolyte.

There are two different models which are used to describe the movements of charges in a circuit:

Conventional current is a model used to describe the movement of charge in a circuit. It flows from the positive terminal to the negative.

Electron flow is a model showing the movement of electrons in a circuit. It flows from the negative terminal to the positive.

A Coulomb (C) is the unit of electrical charge. 1 Coulomb is equal to 1 amp * 1 second (1C=1A*1s)

Charge can be found using the equation Q=It, where Q=charge, I=current and t=time.

An ammeter is an instrument which measures the electrical current that flows within a circuit. They are always connected in series. 

Traditionally ammeters have been made using small coils which…


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