Current:
Electrical charge flow past a given point per unit of time. 

Direct current:
Electrical current that flows in only one direction.

Alternating current:
Electrical current that oscillates forward and backwards.

Voltage:
The ratio of electric potential energy to electric charge at a particular spot in an electric field.  It is often referred to as voltage since it is measured in volts.

Ohm’s law:
Basic law that describe current electricity; Voltage equals current times resistance.

Internal resistance:
Resistance from the processes inside a voltage source; reistance due to the battery itself.

Series circuit:
A circuit where the components form one continuous loop.  The current is constant throughout.

Parallel circuit:
A circuit where each component is connected to form its own separate independent branch.  The voltage is constant throughout.

Fuse/Circuit breaker:
A safety device designed to melt or disconnect a circuit after a predetermined amount of current is exceeded.

Junction rule:
A restatement of conservation of charge; the current going into a junction must equal the current going out of the junction.

Loop rule:
A restatement of conservation of energy; the sum of all voltages in the elements of a loop is zero.

Electric circuits come in a variety of styles.  Regardless of the type, Ohm’s law can be used to find a few basic quantities.  Voltage is equal to current times resistance.  Also, power can be calculated by current times voltage.  When circuit components are arranged one after another in a loop, this is a series circuit.  When the components are arranged in separate, independent connections to the voltage source, that is a parallel connection.  For more complex circuits, with multiple loops or multiple voltage sources, Kirchoff’s laws are the answer.  The junction rule says that charge is conserved.  The loop rule says that energy or voltage is conserved.

Specific Tutorial Features:

• Step by step calculation of complex Kirchoff’s laws problems.
  
• Circuits diagrams simplified into less complex circuits.

Series Features:

• Concept map showing inter-connections of new concepts in this tutorial and those previously introduced.
  
• Definition slides introduce terms as they are needed.
  
• Visual representation of concepts
  
• Animated examples—worked out step by step
  
• A concise summary is given at the conclusion of the tutorial.

Ohm’s law

• Circuit diagrams
  
• Alternating current
  
• Direct current
  
• Internal resistance

Electric power

• Formula
  
• Example calculations

Series circuits

• Resistors combined in series
  
• Current and voltage characteristics
  
• Example calculations

Parallel circuit

• Resistors combined in parallel
  
• Current and voltage characteristics
  
• Example calculations

Kirchoff’s laws

• Junction rule
  
• Loop rule