Physics·Electricity and magnetism · NSSCO 5.2.1
Electric current
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Electricity begins with one simple idea — moving charge. In this lesson we meet the electric current: what it is, the units we measure it in (the coulomb and the ampere), and the equation I = Q ÷ t that links current, charge and time. We learn to measure current with an ammeter connected in series, compare conventional current (+ to −) with the real drift of electrons (− to +), see that current in a metal is a flow of free electrons, and tell direct current from alternating current.
What you'll learn in this lesson
By the end you should be able to (NSSCO Physics 5.2.1):
- Explain that an electric current is a flow of charge, measured in amperes (A) using an ammeter
- Recall and use the equation current I = charge Q ÷ time t
- State that charge is measured in coulombs (C) and that 1 A = 1 coulomb per second
- State and use the correct way to connect an ammeter (in series)
- Distinguish between static electricity and current electricity
- Distinguish the direction of conventional current (+ to −) from the direction of electron flow (− to +)
- Explain that current in a metal is a flow of free electrons, and distinguish direct current (d.c) from alternating current (a.c)
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