phy既current同charge 同voltage

Generally, charge can be considered as a medium to carry energy
in a circuit. For example, in a circuit containing a light bulb and
a cell, charge are reponsible for carrying energy from the cell to the
light bulb, causing it to glow.

As for current, it is the flow of charges within a circuit. The flow of
charge is simply the movement of the charge within a circuit. It is
given by the equation I = Q / t. Therefore, current is the movement of
charge within a particular time, usually 1 (s).

Voltage is, actually, the potential difference (p.d.) within the circuit.
The simple definition of p.d. is the amount of energy needed for a
charge to move from one place to another. It resembles gravitational
potential energy.
Hence, voltage can be defined by the amount of energy carried by
charges through a point within a particular time. That simply means
the amount of energy pocessed by the charge when it flows through
an arbitary testing point within a circuit.
Equation of voltage: V = W / Q,
where W is the amount of energy provided or more generally, work
done by the charge.

Simply speaking, a voltage casues charges to flow. Such flow of charges constitutes an electric current.