Voltage
The impedance of an electric circuit is the measure of the opposition presented by a circuit when the current and voltage is applied.
When that circuit has no breaks. It is an endless path of current flow.
The impedance of electric circuit refers to the measure of the opposition that a circuit presents to a current when a voltage is applied.
A voltmeter is a device to measure the voltage in a electric circuit, and must have be connected in parallel to it.
The volt (symbol: V).
ammeter
Power
Voltage is a measure of electric 'push'. When there's nothing to push (no circuit) it has no meaning, but that isn't to say it isn't there. Just the same as if you push a car. Take the car away and your push goes away. (or does it?)
An ammeter is a measuring instrument used to measure the electric current in a circuit.
The current measured at any point in a simple circuit will be the same because current is the measure of electron flow through a circuit. The current flowing through any branch of any circuit (or an entire simple circuit) will always be the same at any point.
muragapha
You can measure current - or the lack of current - with an ammeter.