Charge and Current Study Guide

Potential difference (p.d.) is measured in volts (V) and represents the energy transferred per unit charge.

Current (I) is measured in amperes (A) and represents the rate of flow of charge.

Charge (Q) is measured in coulombs (C) and represents the quantity of electricity.

The relationship between charge, current, and time is given by: Q = It.

The work done (W) in moving a charge through a potential difference is given by: W = VQ.

A voltmeter is connected in parallel to measure potential difference.

An ammeter is connected in series to measure current.

In a series circuit, the current is the same throughout the circuit.

In a parallel circuit, the potential difference is the same across each branch.

Conventional current flows from positive to negative, opposite to electron flow.

Kirchhoff's Current Law states that the total current entering a junction equals the total current leaving.

Conductors have many free charge carriers (usually electrons).

Insulators have few or no free charge carriers.

Semiconductors have conductivity between conductors and insulators.

One Coulomb (C) is equal to 1 Ampere-second (A·s).

The energy transferred is also known as work done.

Potential difference is sometimes called voltage.

Cells convert chemical energy to electrical energy.

Generators convert mechanical energy to electrical energy.

Batteries are composed of multiple cells.