T5A: Metric prefixes; units and measurement of current, voltage;
concept of conductor and insulator
There are 1000 hertz in a kilohertz. If a dial marked in kilohertz shows a reading
of 28450 kHz, it would show 28,450,000 Hz, if the dial were marked in hertz.
The ampere is the basic unit of electric current. The instrument used to
measure electric current is the ammeter.
If an ammeter marked in amperes is used to measure a 3000-milliampere
current it would show 3 amperes.
The basic unit of electromotive force (EMF) is the volt. The instrument used
to measure electric potential or electromotive force is the voltmeter.
Gold, silver, aluminum are three good electrical conductors. So is
copper. And carbon conducts electricity also.
Glass, air, plastic, porcelain are four good electrical insulators.
Paper, rubber, wood and mica are also insulators.
An open circuit is an electrical circuit that has no current.
A short circuit is an electrical circuit that draws too much current.