Emmett Bradley

2023-02-20

Why is alternating current used in homes?

balkjerepp

Beginner2023-02-21Added 4 answers

The majority of electrical distribution systems employ alternating current for a number of reasons, but the main one is how simple it is to change from one voltage to another.

DC is very much more difficult (and expensive) to do this with.

(To transform DC, electronic circuits are used to generate AC which is then transformed with a transformer and rectified back to DC.)

Huge amounts of AC power can be transformed to almost any desired voltage, with very low energy loss, using an electric transformer (coils with their magnetic fields closely linked).

All "room temperature" conductors have resistance, so they heat up when carrying current.

The heat (transmission loss) generated by this is proportional to the square of the current, and to the resistance:

Energy $={I}^{2}R$

Both resistance and current should be kept at a minimum to reduce energy loss, with low current being especially crucial because it has an exponential impact on losses.

Power $P=V\cdot I$ (volts multiplied by amps) so for a given power, voltage must be high if current is kept low.

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.

AC power is then easily and efficiently transformed to a relatively safe voltage at local transformers near the place of use.

This is not nearly as easy or cheap to do with DC.

Other causes include:

DC is more lethal than AC for the same voltage because it's harder to let go of if touched as the voltage does not go through zero. (Muscles contract with constant force with DC).

Electrolytic corrosion is more problematic with DC.

DC arcs do not "quench" as easily (because voltage does not go through zero).

AC induction motors are simple to make and maintain. DC motors require a commutator and brushes, or complicated electronic switching.

DC is very much more difficult (and expensive) to do this with.

(To transform DC, electronic circuits are used to generate AC which is then transformed with a transformer and rectified back to DC.)

Huge amounts of AC power can be transformed to almost any desired voltage, with very low energy loss, using an electric transformer (coils with their magnetic fields closely linked).

All "room temperature" conductors have resistance, so they heat up when carrying current.

The heat (transmission loss) generated by this is proportional to the square of the current, and to the resistance:

Energy $={I}^{2}R$

Both resistance and current should be kept at a minimum to reduce energy loss, with low current being especially crucial because it has an exponential impact on losses.

Power $P=V\cdot I$ (volts multiplied by amps) so for a given power, voltage must be high if current is kept low.

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.

AC power is then easily and efficiently transformed to a relatively safe voltage at local transformers near the place of use.

This is not nearly as easy or cheap to do with DC.

Other causes include:

DC is more lethal than AC for the same voltage because it's harder to let go of if touched as the voltage does not go through zero. (Muscles contract with constant force with DC).

Electrolytic corrosion is more problematic with DC.

DC arcs do not "quench" as easily (because voltage does not go through zero).

AC induction motors are simple to make and maintain. DC motors require a commutator and brushes, or complicated electronic switching.

The magnetic field inside a long straight solenoid carrying current

A)is zero

B)increases along its radius

C)increases as we move towards its ends

D)is the same at all pointsWhich of the following units is used to express frequency?

Hertz

Watt

Newton

PascalWhat does tangential force produce?

How Many Different $f$ Orbitals Are There?

What is $\frac{e}{m}$ value for electrons ?

Which of the following correctly describes the magnetic field near a long straight wire?

A. The field consists of straight lines perpendicular to the wire

B. The field consists of straight lines parallel to the wire

C. The field consists of radial lines originating from the wire

D. The field consists of concentric circles centered on the wireIs energy directly proportional to frequency?

What is a compass? How is a compass used to find directions?

Magnetic field lines never intersect each other because

There will be two directions of the field at the same point.

Feild lines repel each other

Field lines follow discrete paths only

If field lines intersect they create a new magnetic field within the existing fieldTwo parallel wires carry currents of 20 A and 40 A in opposite directions. Another wire carrying a current antiparallel to 20 A is placed midway between the two wires. The magnetic force on it will be

Towards 20 A

Towards 40 A

Zero

Perpendicular to the plane of the currentWhat is the wavelength of the light emitted when an electron in a hydrogen atom undergoes transition from the energy level n = 4 to energy level n = 2? What is the colour corresponding to their wavelengths? (Given ${R}_{H}=109677c{m}^{-1}$)

A) 486 nm, Blue

B) 576 nm, Blue

C) 650, Blue

D) 450 nm, BlueTwo identical conducting spheres A and B are separated by a distance greater than their diameters the spheres carry equal charges and electrostatic force between them is F a third identical uncharged sphere C is first brought in contact with A, then with B and finally removed as a result, the electrostatic force between A and B becomes

Which of the following radiation has the shortest wavelength.

X-ray

Infra red

microwave

ultravioletHow to find the local extrema for $f\left(x\right)=5x-{x}^{2}$?

Equation $F=ILB$ holds true only if: A. direction of electric current makes an angle of 30 degrees with the direction of magnetic field. B. direction of electric current makes an angle of 120 degrees with the direction of magnetic field. C. direction of electric current is perpendicular to the direction of magnetic field. D. direction of electric current is parallel to the direction of magnetic field.