AC devices?

Question

What are some devices that have been invented as a result of widespread use of AC electricity?

I already have induction cooktops and electric guitars, but a need one more.

One which works only with AC would be best, rather than one that CAN use DC but doesn't.

Answer 1

Induction electric motors.

This is a very simple electric motor that uses the transformer principle and Newton's third law to operate. Since it relies upon the transformer principle to induce a magnetic field on the rotor, it cannot use DC.

Most cheap appliances, such as your blender, mixer, or your electric fan, use induction motors because they are simple to make, and therefore make the appliance itself cheaper as a result.

===edit===
No modern home should be without one – or maybe a dozen. You'll find an induction motor in the fan, fridge, vacuum cleaner, washing machine, dishwasher, clothes drier, and the little pump that circulates water in the fish tank to stop the water turning green and the fish going belly-up. Chances are there's also one in the air conditioner – unless it's a particularly high-tech one.

Advantages:
• Cheap
• Quiet
• Long lasting
• Creates no interference

Disadvantages:
• Wants to turn at constant speed (50Hz divided by half the number of poles)
• Cannot turn faster than 1500rpm (4-pole motor)
• Draws a massive starting current, or is inefficient, or both
• Kind of big and bulky for the power it develops

This one came out of a fan....

===edit2==

I'm not sure what applications that the guy below me is thinking about, since transformers will not work with straight DC; a transformer will work with pulsed DC (which isn't really DC).

An electromagnetic isn't really a transformer, since there is only a primary coil; there is no secondary coil, and no secondary circuit.

Answer 2

A transformer. A transformer is one device that will only work with AC, and is used to step up or step down AC voltages..
Note to the person below. An induction coil or electromagnet are not a transformer, and I repeat, a transformer will not work with DC. However all of them are electromagnetic devices.

Most devices in the home and in industry have a transformer in them.
Some devices include electric welding machines, fridges, stereos, florescent lighting, electric motors, the list goes on....

Answer 3

Transformers most certainly can be used with D/C!!!!!!!! It depends on the application. Electromagnets are transformers (coils) for one.

Insulated Gate Bipolar Transistors (IGBT's) are used in Variable Voltage Variable Frequency (VVVF) drives and other devices that power A/C motors and other devices and are powered only by alternating voltage.

Silicon Controlled Rectifiers (SCR's) are powered by alternating voltage and are used to convert alternating voltage to simulated direct voltage for use on D/C motor drives, electric signs, etc.

Something that most people don't realize is the use of the term "alternating current" is not accurate. VOLTAGE is what is "alternating". CURRENT is the result of RESISTANCE applied to voltage (E=I x R), thus the correct terminology is "alternating voltage". The same applies to D/C or rather (direct voltage).