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Ward Leonard method of speed control is used for controlling the speed of a DC motor. It is a basic armature control method. This control system is consisting of a DC motor M1 and powered by a DC generator G. In this method the speed of the DC motor (M1) is controlled by applying variable voltage across its armature. This variable voltage is obtained using a motor-generator set which consists of a motor M2 (either AC or DC motor) directly coupled with the generator G. It is a very widely used method of speed control of DC motor.

The functional characteristics of a 4 point starter are similar to a 3 point starter. Four point starter works as a current controlling device in the deficiency of back EMF while starts running of the DC motor. A four-point starter also works as a protecting device. The main difference between a 4 point starter compared to a 3 point starter is, the holding coil is detached from the shunt-field circuit. After this, Sit is connected in series with the current limiting resistance (R) across the line.

The output power of any electrical motor is always from the coupling mounted on the shaft because the motor converts electrical power to mechanical power. In case of electric motor (AC or DC), the mechanical power is available at the shaft in horse power.

The organic compound that is used as an antiknock agent in petroleum is tetraethyl lead. This is a lead based organic compound. Antiknock agents are gasoline additives that help in lessening the engine knocking and increasing the octane rating of the fuel at the same time.

Transformer have maximum efficiency at copper loss = iron loss

The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 15 to 35 kilometers (9.3 to 21.7 mi) above Earth, although its thickness varies seasonally and geographically.

Electrical steel (lamination steel, silicon electrical steel, silicon steel, relay steel, transformer steel) is an iron alloy tailored to produce specific magnetic properties: small hysteresis area resulting in low power loss per cycle, low core loss, and high permeability.

Electrical steel is usually manufactured in cold-rolled strips less than 2 mm thick. These strips are cut to shape to make laminations which are stacked together to form the laminated cores of transformers, and the stator and rotor of electric motors. Laminations may be cut to their finished shape by a punch and die or, in smaller quantities, may be cut by a laser, or by wire EDM.

Both radar and sonar locate objects from the echo of a signal that is bounced off the object. Radar uses radio waves, which are a type of electromagnetic energy. Sonar uses the echo principle by sending out ultrasonic sound waves underwater or through the human body to locate objects. Sound waves are a type of acoustic energy.

An Aeroplane relies on Bernoulli’s Principle to generate lift on its wings. A Helicopter uses the same method to generate lift on its wings. A Race-car uses Bernoulli’s principle to stay on the ground (down force). An Insecticide Spray also uses Bernoulli’s Principle to spread out the spray over a larger area. Bernoulli’s principle also explains how spray bottles work. When a fluid passes over the top, it is moving at a high speed with low pressure. The water below is not moving, and therefore has a greater pressure. The high pressure fluid rises up the tube to meet the low pressure fluid. Because the low pressure fluid is moving at a high speed, it pushes the water out of the bottle.

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