# Voltage frequency and current relationship

### What is the relation between frequency and voltage | All About Circuits

Current frequency relationship. Electrically excitable cells (also called neurons) generate a series of voltage pulses in responses to different input as currents. Nov 5, Hi How can it be that the frequency is 50 Hz and voltage is V in the because any appliance of a certain power draws double the current. Alternating current (AC) is an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which electric power is delivered to . Even at relatively low frequencies used for power transmission (50 Hz – 60 Hz), non- uniform distribution.

Standard power utilization voltages and percentage tolerance vary in the different mains power systems found in the world.

High-voltage direct-current HVDC electric power transmission systems have become more viable as technology has provided efficient means of changing the voltage of DC power. Transmission with high voltage direct current was not feasible in the early days of electric power transmissionas there was then no economically viable way to step down the voltage of DC for end user applications such as lighting incandescent bulbs.

Three-phase electrical generation is very common.

In practice, higher "pole orders" are commonly used. The advantage is that lower rotational speeds can be used to generate the same frequency.

If the load on a three-phase system is balanced equally among the phases, no current flows through the neutral point. Even in the worst-case unbalanced linear load, the neutral current will not exceed the highest of the phase currents.

Harmonics can cause neutral conductor current levels to exceed that of one or all phase conductors. For three-phase at utilization voltages a four-wire system is often used. When stepping down three-phase, a transformer with a Delta 3-wire primary and a Star 4-wire, center-earthed secondary is often used so there is no need for a neutral on the supply side.

For smaller customers just how small varies by country and age of the installation only a single phase and neutral, or two phases and neutral, are taken to the property. For larger installations all three phases and neutral are taken to the main distribution panel. From the three-phase main panel, both single and three-phase circuits may lead off. Three-wire single-phase systems, with a single center-tapped transformer giving two live conductors, is a common distribution scheme for residential and small commercial buildings in North America.

This arrangement is sometimes incorrectly referred to as "two phase". A similar method is used for a different reason on construction sites in the UK. A third wirecalled the bond or earth wire, is often connected between non-current-carrying metal enclosures and earth ground. This conductor provides protection from electric shock due to accidental contact of circuit conductors with the metal chassis of portable appliances and tools.

Bonding all non-current-carrying metal parts into one complete system ensures there is always a low electrical impedance path to ground sufficient to carry any fault current for as long as it takes for the system to clear the fault. This low impedance path allows the maximum amount of fault current, causing the overcurrent protection device breakers, fuses to trip or burn out as quickly as possible, bringing the electrical system to a safe state.

### Voltage, Current, and Frequency Summary

AC power supply frequencies[ edit ] Further information: A low frequency eases the design of electric motors, particularly for hoisting, crushing and rolling applications, and commutator-type traction motors for applications such as railways.

However, low frequency also causes noticeable flicker in arc lamps and incandescent light bulbs. The use of lower frequencies also provided the advantage of lower impedance losses, which are proportional to frequency. Effects at high frequencies[ edit ] Play media A Tesla coil producing high-frequency current that is harmless to humans, but lights a fluorescent lamp when brought near it A direct current flows uniformly throughout the cross-section of a uniform wire.

An alternating current of any frequency is forced away from the wire's center, toward its outer surface. This is because the acceleration of an electric charge in an alternating current produces waves of electromagnetic radiation that cancel the propagation of electricity toward the center of materials with high conductivity.

### What is relation between frequency and voltage?

This phenomenon is called skin effect. At very high frequencies the current no longer flows in the wire, but effectively flows on the surface of the wire, within a thickness of a few skin depths.

For example, the skin depth of a copper conductor is approximately 8. Since the current tends to flow in the periphery of conductors, the effective cross-section of the conductor is reduced.

This increases the effective AC resistance of the conductor, since resistance is inversely proportional to the cross-sectional area. The AC resistance often is many times higher than the DC resistance, causing a much higher energy loss due to ohmic heating also called I2R loss. Now, reverse the battery connections to the bulb. It still is as bright as before, still dissipates w.

The difference is, the voltage across the bulb is the opposite of what it was before, and the current is the opposite also, but when they are multiplied, the power is still positive. Suppose you reverse the connections 60 times per second, or, or a million. How much power does the light bulb dissipate?

## Alternating current

The same, because there is no time when V times I is not equal to w. Typical wall power is not like that, of course.

AC Voltage Circuts (Cycles, Periods, & Frequency)

Rather than instantaneously switching between positive and negative voltage, it swings smoothly with a sinusoidal curve. So the light bulb dissipates maximum power when the voltage is maximum in the positive direction, zero when the voltage is zero, and maximum again when the voltage is maximum in the negative direction.

So if the wall frequency is 60hz or 50hz or hz in some airplanesthe power dissipation actually varies between maximum and zero at a rate of twice that. But since the filament takes a longer time to get hot and cool down, it seems to be on steadily. The running average power is constant.