Difference Between AC and DC Motor

AC vs DC Motor 

An electromechanical device converts electrical energy to mechanical energy. AC motor is an electromechanical device that works on AC electricity while the DC motor works on DC electricity.

More about AC motor

An AC motor consists of two main parts a rotor, a component that rotates, and a stator, which is stationary. Both have coil windings to create a magnetic field and the repulsion of the magnetic field creates the rotor to move. The current is delivered to the rotor through slip rings, or permanent magnets are used. The kinetic energy of the rotor delivered to shaft connected to the rotor and the torque generated act as the driving force of the machinery.

There are two main types of AC motors. Induction motor, which runs more slowly than the frequency of the source, is the first type. The synchronous motor is designed to avert this effect of induction; therefore runs at the same frequency or a sub-multiple of the frequency.

AC motors can produce a large torque. Because of the power source used, it can be designed to draw large amounts of power. Power mains can supply very large currents required for the operation of the heavy duty motors. Most common AC motors use the squirrel cage rotor, which is found almost in all domestic and light industrial AC motors. Most domestic appliances like a washing machine, dishwasher, standalone fan, record player, etc. use some variant of a squirrel cage rotor.

AC motors are designed for three phase, two phase, and single phase power sources. Depending on the requirement the usage of the motor type varies.

More about DC motor

Two types of DC motors are in use; they are the Brushed DC electric motor and Brushless DC electric motor. The fundamental physical principle behind the operation of DC and AC motors are the same.

In brushed motors, brushes are used to maintain electrical connectivity with the rotor winding, and internal commutation changes the polarities of the electromagnet to keep the rotational motion sustained. In DC motors, permanent or electromagnets are used as stators. In a practical DC motor, the armature winding consists of a number of coils in slots, each extending for 1/p of the rotor area for p poles. The number of coils in small motors may be as low as six, and it may be as high as 300 in large motors. The coils are all connected in series, and each junction is connected to a commutator bar. All coils under the poles contribute to torque production.

In small DC motors, the number of windings is low, and two permanent magnets are used as the stator. When higher torque is needed the number of windings and magnet strength are increased.

The second type is brushless motors, which has permanent magnets as the rotor and electromagnets are positioned in the rotor. A high power transistor charge up and drives the electromagnets.

What is difference between AC motor and DC motor?

• AC motor works on AC electricity while DC motor works on DC electricity.

• General DC motors deliver less torque power than the AC motors.

• AC motor requires a starter mechanism, but the DC motors do not need a starter mechanism.

• DC motors are single phase motors whereas AC motors are both 1 and 3 phases.

Difference Between Vitamin D and Vitamin D3

Vitamin D vs Vitamin D3

If you have been advised a series of vitamins and are wondering about their effects, here are a few facts you need to know about vitamin D. It is one of the more complex vitamins that are needed by the human body in order to grow and develop. Vitamin D is actually available in two forms, cholecalciferol and Ergocalciferol, better known as vitamin D3 and vitamin D2. First things first. Vitamin D can be found in 2 forms. Vitamin D2 is manufactured by plants or fungus. You would include it through fortified foods such as juices, milk or cereals. However, vitamin D3 is formed when the body synthesizes sunlight on its surface. It mainly occurs through the exposure of the skin to UVA and UVB rays. Vitamin D3 can also be obtained by consuming animal products. It is also interesting to note that since it is produced in the body, vitamin D is actually considered a hormone and not really a vitamin! Vitamin D is very important as it regulates the production of phosphorous and calcium in the body. The Vitamin D that you purchased so willingly over the counter in the form of medication can actually be very harmful without supervision. You see, one of the forms of vitamin D, i.e. vitamin D2 is broken down by the body into different substances. Some of these substances can be very harmful for the body. Vitamin D3 is broken down by the body into a substance called calcitrol, which actually has very important cancer fighting properties. The supplements for vitamin D may be made from either plants or animals. However, if you were looking for a vitamin D3 supplement, you would look for only those available through animal supplements. It is also available from lamb’s wool! Vitamin D is frequently added to a number of foods, to make them beneficial. However, if you were looking for vitamin D3 in particular, you would have to go for a pill or a liquid form. It is not very common to find it in cereals or juices. Another important difference is that vitamin D2 has a shorter shelf life compared to vitamin D3. This decreases the potency of the vitamin if it is used as a vitamin supplement. Some researchers however feel that their efficacy is the same.
Summary: 1. Vitamin D is manufactured by both plants and animals. Vitamin D3 is particularly found on the skin of animals, as a byproduct of synthesis.
2. Vitamin D is not beneficial in all its forms. Vitamin D2, one of the forms of vitamin D can be toxic to the body. Vitamin D3 is good for the body.
3. You can get vitamin D from fortified foods or as pills. However, vitamin D3 is only available in the form of pills or in liquids. They are rarely found in foods.
4. Supplements for the two vitamins are sourced differently.
5. The D2 form of the vitamin has a shorter shelf life compared to the D3 form.

Difference Between LCD and LED Televisions

LCD vs LED Televisions

The LCD television is a flat-panel television which utilizes a Liquid Crystal Display technology. It has two layers of glass which are polarized and stuck together. The liquid crystals are held in one of the layers. These liquid crystals pass, or block the light, to produce images on the screen when the electric current passes through it. However, the crystals do not produce their own light. The light comes from the series of fluorescent lamps at the back of the screen. There are millions of shutters arranged in a grid, which open and close to release and trap some of the light that is not needed to create images. Then each shutter is paired with a colored filter which produces a sub-pixel. These are so small, that when they combine, they create a single pixel, which appears to be a single spot of color on the screen. With the help of the fluorescent lamps, the images created by the liquid crystals become visible to the viewer. LCD television produces high image quality. They can be made very thin, which makes them less space-consuming, and the user can hang them anywhere. This makes them appealing to buyers. LED TV’s are actually very much like LCD TV’s. They also have a flat-screen which utilizes Liquid Crystal Display technology. The only difference is their source of light, which is at the back of the screen. The LCD TV uses fluorescent lamps, and the LED TV uses LED (Light Emitting Diodes). There are two types of LED backlighting. One is referred to as Edge lighting, and the other is called Full-Array lighting. With the Edge lighting, the series of diodes are arranged along the outside edges of the screen. When there is power, the light is distributed across the screen. Alternatively, in Full-Array lighting, there are several rows of diodes behind the entire surface of the screen. They provide more control over brightness and dimming, because the diodes can be turned on and off independently. LED TV’s are LCD TV’s with a new backlight system. They are newly developed for LCD’s, because Light Emitting Diodes are said to give more balance in color saturation, and use less power than the fluorescent lamps. LED TV’s are the newest version, and that’s why they are currently more expensive than the standard LCD TV’s.
Summary: LED TV’s are still LCD TV’s. They are just considered to be the newer LCD TV version because of the new backlight system used. The LED TV uses Light Emitting Diodes, while the standard LCD TV uses fluorescent lamps. Although they both still use Liquid Crystal Display technology. The main difference is the part behind their screen, which is the backlight.