Voltmeter and Ammeter

Voltmeter
A voltmeter is an instrument used for measuring the electrical potential difference between two points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage by use of an analog to digital converter.

Ammeter
An ammeter is a measuring instrument used to measure the electric current in a circuit. Electric currents are measured in amperes (A), hence the name.

Electricity

Electric Current
Electric current is whenever electric charge moves. Electric current is the rate of charge flow past a given point in an electric circuit, measured in Amperes. The standard abbreviations for the units are 1 A.
Electric Charge
Electric charge, also called "electricity," is a funamental component of everyday matter. Objects are made of molecules and atoms, atoms are made of protons, neutrons, and electrons, and the protons and electrons are made in part out of electric charge.

Electric Field
When positive charges attract negative charges, there is an electric field joining the charges together. Electric fields are a lot like magnetism. However, electric fields are NOT MAGNETIC.

Electrons.
Whenever an electric current appears in a copper wire, the electrons already present within the copper are forced to flow. Batteries and generators don't put those electrons into the wires. The electrons were already there, because wires are made partly of electrons.

Voltage
Voltage is one way that we can measure an electric field. In a battery circuit, the voltage from the battery causes the charges of the wire to flow. VOLTAGE CAUSES CURRENT.