What is Alternating current: Definition and 121 Discussions

Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, fans and electric lamps into a wall socket. A common source of DC power is a battery cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage.The usual waveform of alternating current in most electric power circuits is a sine wave, whose positive half-period corresponds with positive direction of the current and vice versa. In certain applications, like guitar amplifiers, different waveforms are used, such as triangular waves or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. These types of alternating current carry information such as sound (audio) or images (video) sometimes carried by modulation of an AC carrier signal. These currents typically alternate at higher frequencies than those used in power transmission.

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  1. B

    Exploring How a Generator Produces Alternating Current

    Homework Statement How does a loop of wire in a generator produce alternating current? a.by creating current by rotating in an existing magnetic field? b.by creating a varying magnetic field with its rotational kinetic energy c.by rotating through areas of high and low electrical force...
  2. B

    How does a loop of wire in a generator produce alternating current?

    a.by creating current by rotating in an existing magnetic field? b.by creating a varying magnetic field with its rotational kinetic energy c.by rotating through areas of high and low electrical force An electric field produces a magnetic field even when there is no wire to conduct a...
  3. S

    Hall effect under alternating current condition

    Can someone please pore some light on the entitled topic. Assume that i path an AC current through conductor. Dose it produces Hall effect? furthermore, assume that the conductor is non-symmetric, namely it is coating with another conducting thin film layer. Now is there any frequency under...
  4. H

    Alternating current versus direct current

    i am currently going over ac and dc currents in school but i want to know more but my teacher isn't going very deep into this subject. Can you help me out please?
  5. A

    How Does Adding a Capacitor Affect Current in an AC Circuit?

    Homework Statement A light bulb has a resistance of 212 . It is connected to a standard wall socket (120 V, 60.0 Hz). (a) Determine the current in the bulb. (b) Determine the current in the bulb after a 13.2-μF capacitor is added in series in the circuit. Homework Equations R, V, f are...
  6. rohanprabhu

    Doesn't Alternating current cause fatigue?

    Take the case of a lamp bulb. When applied an Alternating current across it.. it basically goes on and off 50 times in a second [in India atleast.. we get 50Hz]. Now, it means that the filament gets hold and cold continuously. From wikipedia: so.. is alternating current more damaging for...
  7. rohanprabhu

    Alternating current : Solving for low-pass filter

    Homework Statement Q] The figure below shows a typical circuit for a low-pass filter. An AC input V_i~=~10~mV is applied at the left end and the output V_o is received at the right end. Find the output voltage as a function of \nu~(\textrm{frequency})...
  8. A

    AC Frequency: Calculating from V, I, & t

    Homework Statement A light bulb is connected to a 120.0-V wall socket. The current in the bulb depends on the time t according to the relation I = (0.669 A) sin [(491 Hz)t]. What is the frequency of the alternating current? Homework Equations How do I use the given value for I...
  9. K

    Understanding Alternating Current Supply in Households

    My Question is this- We get AC supply to our houses, So for the first half cycle the current should from thro the live wire to the load and then return thro neutral, Now for the 2nd half cycle this must be reveresed, That is Neutral-load-Phase. This is wat is Alternating current. But I...
  10. M

    Transformers and Impedance Matching

    Hey all, any help with any of these problems would be greatly appreciated, I have attempted all but one(because I do not even know where to start). Homework Statement A 58.0 resistor, a 3.00 µF capacitor, and a 0.400 H inductor are connected in series to a 77.0 V (rms), 60.0 Hz source. (a)...
  11. M

    Understanding Alternating Current (AC)

    Im new to electronics and the whole concept of AC current is making my brain hurt. From what I've gathered AC current unlike DC moves back and forth. The electrons don't just flow straight around the circuit but theyre constantly moving back and forth. When it comes to Hertz and...
  12. M

    Measuring Inductance in an LR Circuit with AC

    In an LR circuit with alternating current , it is know that the inductance of the cable is of the order 10^-7 . With a 2 ohm resistor ,the circuit is used to measure inductance.There are 2 frequencies , 100kHZ and 1M Hz,that can be chosen for the measurement . So whyI MHz is better . I know...
  13. A

    Alternating current about resonance width

    Since the question quite long and contains many formulas, so i take a photo instead. my question is that for part b since Z= \sqrt{R^2+(X_L-X_C)^2} can i subst X_L = (W_0+\triangle{\omega})L and X_C = \frac{1}{(w_0+\triangle{\omega})L} into the Z= \sqrt{R^2+(X_L-X_C)^2}...
  14. A

    High frequency high power alternating current

    Hi, When you have a high frequency high power alternating current, Can you use a regular wire to transmit the current or do you have to use a waveguide? Or some kind of combination? Thanks.
  15. G

    Alternating Current vs Direct Current

    Can someone explain breifly or in detail :biggrin: the differnece between ac and dc. Maybe advantages and disadvantages. From what i have researched i know that ac the current flows in every direction while in dc it only flows in one. In ac the voltage can be put down and up using transformers...
  16. P

    AC Voltage: Is 110V Always Supplied?

    When the generator produces electricity,during the revolutions of the coil,the voltage induced is changing.If the voltage supply of a certain country is 110V, will the voltage supplied is NOT 110V sometimes? Also, the current induced when the coil is set vertically,will the appliance stop...
  17. R

    Alternating current wave prob

    alternating current wave prob... assume the wave is sinusoidal. suppose that each horizontal division (13) represents 1.0 ns and that each vertical division (11) represents 1 mV. what is the approx. rms voltage? please help me solve this. i am not so sure how to find rms, and if you do...
  18. S

    Question regarding alternating current

    When an a.c. flows in a resistor,the mean power dissipated is P.If the frequency of the a.c. is doubled with the same value of peak voltage,what id the average power dissipated now ? My solution : P = (I_rms)^2 R I assume that as the peak voltage remains the same and the mean power...
  19. D

    What's Inside the Mystery Box with AC and DC Circuits?

    Two connections allow contact with two circuit elements in series inside a box, but it is not known whether the circuit elements are R,L, or C. In an attempt to find what is inside the box, you make some measurements with the following results. When a 3.0-V dc power supply is connected across...
  20. S

    Alternating Current Circuits and Electromagnetic Waves

    Just wanted to know if someone could help me out or check my answers. The Transformer 38) A step-down transformer is used for recharging the batteries of portable devices such as tape players. The turns ratio inside the transformer is 13:1 and it is used with 120V (rms) household service. If...
  21. R

    Discover the Basics of Alternating Current in Electrical Circuits

    What is alternating current?
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