5.1 Voltage, Resistance, and Current

Module 5 of the Navy Basic Electricity and Electronics series starts today. This module is called Relationships of Current, Voltage, and Resistance. The first four modules were:

1. Electrical Current
2. Voltage
3. Resistance
4. Measuring Current and Voltage in Series Circuits

The first section of the new module is titled: "Voltage, Resistance, and Current." "The relationship of voltage, resistance, and current is probably the most important concept you will learn in your study of electricity" (6).

• You cannot really address current directly. You can only change it by increasing the force moving it (relates to voltage) or the resistance opposing it.
• When voltage goes up, current goes up. When voltage goes down, current goes down (assuming that resistance is held constant).
• So the amount of current is "directly proportional" to the amount of voltage.
• When resistance goes up, current goes down. When resistance goes down, current goes up (assuming voltage is constant). 
• EMF (electromotive force, which relates to voltage) and resistance are inherent quantities that depend on the physical components you are using in a circuit. Current is a secondary characteristic--it changes on the basis of the physical components.
• The relationships between voltage, resistance, and current were unfolded by George Simon Ohm (1789-1854). Ohm's Law states, "Current is directly proportional to voltage and inversely proportional to resistance."