Does the light switch use direct current or alternating current?

Answer 1

A direct current flows only in one direction. An alternating current changes its direction of flow in a regular (cyclic) way, all the time and usually several times per second.

Other answers

An alternating current (AC) is an electrical current whose magnitude and direction vary cyclically, as opposed to direct current, whose direction remains constant.

The usual waveform of an AC power circuit is a sine wave, as this is the way the electricity is generated in the power plants. It also allows us to efficiently transmit the energy by transforming it to a higher voltage.

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Alternating current is an electrical current whose magnitude and direction vary cyclically. The direction of direct current remains constant. The frequency of the electrical system varies by country. Most electric power is generated at either 50 or 60 Hertz (cycles per second).

In electronic equipment, different waveforms are used, such as triangular, sawtooth or square waves, the latter form being the "heart and soul" of digital computers and modern communications.

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During just one cycle of a single-phase alternating supply, the "live" or "hot" wire of an alternating voltage (or current) supply goes from zero to its positive peak, then back to zero, then continues on to its negative peak and back to zero again.

These positive- and negative-going parts of each cycle are always voltages (or currents) relative to the "neutral" wire. A neutral wire is necessary to allow the currents to return to the alternator.

In a 60 hertz supply there are 60 such cycles in each and every second. Similarly, there are 50 such cycles in each and every second in a 50 hertz supply.

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The voltage in the "live" or "hot" wire usually follows a waveform very close to a perfect sine wave.

Depending on the voltages and currents required, alternators can be, for example, very large power generating machines installed at power stations or the much smaller type of alternators which are fitted into vehicles.

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AC, or Alternating Current, does exactly what the name implies. In USA, Canada - and in other countries which use the same service frequency - the direction of the current changes 60 times a second (also called a frequency of 60 Hertz) between the 'Hot' (also known as the 'Live') wire - often colored Black - and the Common (also known as the 'Neutral') wire, which is usually colored White. In Europe and many other areas of the world, the service frequency is 50 times a second (50 Hertz).

It is the service frequency which makes the typical "humming" sound you hear from Transformers or electric AC motors when they are running.

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The good link below "AC, DC and Electrical Signals" gives a lot more information about the difference between alternating current and direct current.
Direct Current and Alternating Current:

The first and simpler type of electricity is called direct current, abbreviated "DC". This is the type of electricity that is produced by batteries, static, and lightning. A voltage is created, and possibly stored, until a circuit is completed. When it is, the current flows directly, in one direction. In the circuit, the current flows at a specific, constant voltage (this is oversimplified somewhat but good enough for our needs.)

The other type of electricity is called alternating current, or "AC". This is the electricity that you get from your house's wall and that you use to power most of your electrical appliances. Alternating current is harder to explain than direct current. The electricity is not provided as a single, constant voltage, but rather as a sinusoidal (sine) wave that over time starts at zero, increases to a maximum value, then decreases to a minimum value, and repeats.

Answer 2

Direct current means that the current flows in only one direction. Alternating current means that the current is constantly being reversed back and forth on a periodic basis.

More detailed answer

Direct current (dc) flows only in one direction and alternating current (ac) flows alternately forwards and backwards, also varying its amplitude to a peak and returning to zero, at a definite frequency measured in cycles per second. (These are called "hertz", also abbreviated to Hz).

The commonest frequencies for ac electricity supplied to homes and businesses are either 50 Hz or 60 Hz (50 or 60 cycles per second) which means that the ac current changes its direction either 100 or 120 times per second.

Alternating current can be transformed, which means that its voltage can be increased or decreased, by using a transformer.

Direct current can only be decreased and this is done by using a resistance.

Direct current can also be converted into alternating current by using a vibrator (nowadays called an invertor)which changes over its poles many times per second.

Ancient radio receivers used a vibrator to be able use s transformer to transform the direct current of a battery into alternating current, making it possible to increase the basic dc battery voltage (6V) to 400V, as was required by the plate of a tube valve.

Answer 3

The light switch uses whatever type of current the circuit gives it. In a flashlight it is DC, in most home lighting it is AC, in LVDC outdoor home lighting it is DC, etc.