# Why does AC current flow on surface?

Due to skin effect, the AC current tends to concentrate near the surface of a conductor. In case of DC, the current is uniformly distributed over the conductor cross-section area. Skin effect exists for AC and it reduces the effective CSA of the conductor and hence increase the resistance (R = rho*l/A).

The electric current flows mainly at the “skin” of the conductor, between the outer surface and a level called the skin depth. The skin effect causes the effective resistance of the conductor to increase at higher frequencies where the skin depth is smaller, thus reducing the effective cross-section of the conductor.

Also Know, does AC current flow from positive to negative? Current direction Conventional current flows from the positive pole (terminal) to the negative pole. Electrons flow from negative to positive. In an alternating current (AC) circuit the two poles alternate between negative and positive and the direction of the current (electron flow) reverses periodically.

Considering this, how does AC current flow?

In an alternatingcurrent circuit, voltage periodically reverses itself. When the voltage reverses, so does the direction of the current flow. The electrons in an AC circuit don’t really move along with the current flow. Instead, they sort of sit and wiggle back and forth.

Why does AC current change direction?

Every so often, the electrons change direction. In alternating current, the electrons don’t move steadily forward. Instead, they just move back and forth. When the electrons in alternating current switch direction, the direction of current and the voltage of the circuit reverses itself.

### Is lightning DC or AC?

Lightning cannot be AC, since the wave shape of Lightning current is not sine-wave shaped voltage. A typical lightning current waveform looks something like this as shown below. This complete event (A, B and C) is a single strike. Therefore, Lightning is neither DC nor AC.

### What is Corona and skin effect?

“Corona is a discharge caused by electrical over stress.” Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor, and decreases with greater depths in the conductor.

### How is current measured?

Current can be measured using an ammeter. Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient. Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current.

### How does current flow?

Current is flow of electrons, but current and electron flow in the opposite direction. Current flows from positive to negative and electron flows from negative to positive. Current is determined by the number of electrons passing through a cross-section of a conductor in one second.

### Why is there no skin effect in DC?

Direct current also produces magnetic filed around it but it is not alternating, so an alternating magnetic field cannot induce current in a stationary object. So there is no skin effect.

### What is skin depth formula?

Skin depth defines the distance a wave must travel before its amplitude has decayed by a factor of 1/e. The skin depth is the reciprocal of the decay constant β. Thus: δ=1β=1ω(μϵ2[(1+σ2ϵ2ω2)1/2−1])1/2. Since β depends on the frequency and the physical properties of the media, so does the skin depth.

### What do you mean by skin depth?

Skin Depth is a measure of how closely electric current flows along the surface of a material. At d.c. (0 Hz or a constant voltage), electric current flows uniformly through a conductor. This means the current density is the same everywhere.

### How does current flow in metals?

An electric current flows when electrons move through a conductor, such as a metal wire. Metals are good conductors of electricity. Electricity passes through metallic conductors as a flow of negatively charged electrons. The electrons are free to move from one atom to another.

### Why DC current is not used in homes?

Large transformers are used to run transmission lines at high voltages in order to keep losses to a minimum. But high voltage is dangerous, particularly to life, so bringing it into a house would not be an acceptable risk. DC arcs do not “quench” as easily (because voltage does not go through zero).

### How is AC converted to DC?

A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification, since it “straightens” the direction of current.

### Why is ac more dangerous than DC?

One of the reasons that AC might be considered more dangerous is that it arguably has more ways of getting into your body. Since the voltage alternates, it can cause current to enter and exit your body even without a closed loop, since your body (and what ground it’s attached to) has capacitance. DC cannot do that.

### Why sine wave is used in AC supply?

Why we use sine wave is, because in synchronous generator, the nature of field mmf is rotating, which induces alternating or almost sinusoidal emf, which is desired in most of the universal machines. Another reason is the rms value for sine wave is more than that in triangular wave.

### Why do we use AC current?

The voltage in AC circuits also periodically reverses because the current changes direction. AC also has some useful properties, such as being able to convert voltage levels with a single component (a transformer), which is why AC was chosen as the primary means to transmit electricity over long distances.

### How AC power is generated?

The machines which are used to generate electrical voltages are called “GENERATORS”. A.C voltage may be generated by rotating a coil in a magnetic field or by rotating a magnetic field within a stationary coil. •The basic principle of an alternator is the principle of Electromagnetic. Induction.