AC and DC

Created by Jihoon Lee Claimed by Cal Elwer Fall 2016

The Main Idea

What are AC and DC?

AC and DC are different types of voltage or current used for the conduction and transmission of electrical energy. DC, or direct current, is the steady constant current in a circuit consisting of a battery and a resistor that moves in one direction. On the other hand, AC, or alternating current, changes over time in an oscillating repetition. When home appliances such as floor lamps are used, two slots of the wall socket supply a sinusoidally varying voltage, or AC voltage, to drive a sinusoidally varying current in the lamp. Due to AC's wave-like motion, AC can travel far distances efficiently compared to other currents. Typical home appliances which is powered by currents fundamentally from a far distance uses AC. Battery powered objects such as flashlights uses DC power. Electrons from the battery travel in one direction at a steady rate.

~AC currents are not always oscillating in sinusoidal motion, although most buildings and homes have sinusoidal AC currents. Other types of currents include:

The square wave, which is often used in digital electronics

The triangle wave, which is often used in sound synthesis

The importance is that the voltage is alternating over time. Here is a visualization of an AC current in the the alternating current of this water pump

Using the same water pump concept, here is a vvisualization of a DC current. The water can only flow in one direction.

A Mathematical Model

AC POWER Calculation

A "110 volts AC" has a sinusoid varying between "-155V" and "+155V". How does this happen?

When the input value for Vrms is 110 V, ΔVmax comes out to be 155 V which proves that the amount of energy delivered by both "110 V AC" and sinusoid varying between "-155V" and "+155V" are the same.

Connectedness

1. How is this topic connected to something that you are interested in?

"Matter & Interactions" - Electric & Magnetic Interactions only provide RC calculations in-depth. However, in real life we encounter other kinds of circuits such as AC and DC.

1. How is it connected to your major?

Chemical Engineering requires the understanding of how various circuits work in order to create more efficient batteries and how batteries provide energy to the machines.

1. Is there an interesting industrial application?

AC circuits and DC circuits are already used daily in almost every objects that require electricity to function.

See also

Further reading

Charge in a RC Circuit

Current in a RC circuit

External links

http://www.allaboutcircuits.com/textbook/alternating-current/chpt-1/principles-of-radio/.html

http://www.animations.physics.unsw.edu.au/jw/AC.html

References

Chabay, Ruth W. Matter and Interactions: Electric and Magnetic Interactions. : John Wiley, 2015. Print.