Iron Core Solenoids

An iron core has the effect of multiplying greatly the magnetic field of a solenoidcompared to the air core solenoid on the left.

Electromagnet Electromagnets are usually in the form of iron core solenoids. The ferromagnetic property of the iron core causes the internal magnetic domains of the iron to line up with the smallerdriving magnetic field produced by the current in the solenoid. The effect is the multiplication of the magnetic field by factors of tens to even thousands. The solenoid field relationship is and k is the relative permeability of the iron, shows the magnifying effect of the iron core.

Induction Motor Actions

Induction motors use shorted wire loops on a rotating armature and obtain theirtorque from currents induced in these loops by the changing magnetic fieldproduced in the stator (stationary) coils.

At the moment illustrated, the current in the stator coil is in the direction shown and increasing. The induced voltage in the coil shown drives current and results in a clockwise torque. Note that this simplified motor will turn once it is started in motion, but has no starting torque. Various techniques are used to produce some asymmetry in the fields to give the motor a starting torque.

DC Motor Operation

This is an active graphic. Click on bold type for further illustration.

AC Motors

AC Motor As in the DC motor case, a current is passed through the coil, generating a torque on the coil. Since the current is alternating, the motor will run smoothly only at the frequency of the sine wave. It is called a synchronous motor. More common is theinduction motor, where electric current is inducedin the rotating coils rather than supplied to them directly. One of the drawbacks of this kind of AC motor is the high current which must flow through the rotating contacts. Sparking and heating at those contacts can waste energy and shorten the lifetime of the motor. In common AC motors the magnetic field is produced by an electromagnet powered by the same AC voltage as the motor coil. The coils which produce the magnetic field are sometimes referred to as the "stator", while the coils and the solid core which rotates is called the "armature". In an AC motor the magnetic field is sinusoidally varying, just as the current in the coil varies.

SIMPLE ELECTRIC MOTOR

This site features award-winning, easy-to-build, and inexpensive electric motors originally designed by Stan Pozmantir for his science fair project in 1997-2000. If you are looking for a simple science project, or if you wish to learn about electricity, magnetism, and electric motors, this web site has it all! It includes assembly instructions, a section devoted to how these motors work, and here you can find all parts necessary to build these motors. The brushless DC motors shown on this site are extremely simple, and at the same time very stable, reliable, and efficient. The reed switch motor is the easiest electric motor anyone can build (and understand how it works!). The motors shown on this page were widely used for educational purposes in different schools and colleges in the United States and other countries. The kits listed here helped the students to learn basics of electricity, magnetism, and electronics. Many people successfully built these motors using simple and clear instructions that were first published in May 1999.

Riders urged to join highvis demo

Motorcyclists have been urged to join a protest this Saturday against the threat of compulsory high-visibility vests and other restrictive new rules from Brussels.

The Motorcycle Action Group is staging a demonstration rally in Birmingham against proposed anti-tampering rules to stop riders modifying their bikes across Europe and plans for compulsory day-glow bibs in France and Ireland. 

A spokesman for the group said: “Mandatory high-vis vests, an end to riders being allowed to modify their bikes and a host of other horrors being foisted on riders by European politicians will be the subject of a major demonstration.

"MAG is joining other rider organisations across Europe to campaign against proposals that have already seen more than 100,000 riders demonstrate in cities across France."

MAG President Ian Mutch said there was a danger compulsory high-vis could "filter through" from France to other member states through EU harmonisation.

French riders are also facing proposals to outlaw filtering and ban bikes over seven years old from entering cities.

Meanwhile the European Commission is proposing measures to prevent engine and drive train modifications on bikes throughout Europe, at the same time as mandating ABS.

Mutch said, "We’re facing an anti-motorcycling onslaught from politicians in different parts of Europe.  We need to show our own politicians that riders do not want to see further interference spread to the UK."

Protestors plan to gather at midday in the Hare and Hounds car park, Lickey Road, Rednall, B45 8UU.

High Speed Motorbike Cops Car Chase

Recovery after traffic accidents

Kugeluhr - 3

Rubberband gun

Diddis_Pendelaufzug

THE WORLDS BIGGEST MACHINE V CAT D8R

THE WORLDS BIGGEST MACHINE V CAT D8R

Stairs Marble Machine, Daniel Packer

First Marble Machine in action

Marble Machine - Ring Gear Lift - Figure 8 Transfer - Vortex Funnel

Big Marble machine: 1000 marbles!!!

Small marble machine chronicle

Quad marble machine (Take 2)

Micro line following robot (Li-Po battery)

Quad marble machine

Marble machine chronicle

Electric motor

Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force. The reverse process, producing electrical energy from mechanical energy, is done by generators such as an alternator or a dynamo; some electric motors can also be used as generators, for example, a traction motor on a vehicle may perform both tasks. Electric motors and generators are commonly referred to as electric machines.

Electric motors are found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives. They may be powered bydirect current, e.g., a battery powered portable device or motor vehicle, or by alternating currentfrom a central electrical distribution grid or inverter. The smallest motors may be found in electric wristwatches. Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses. The very largest electric motors are used for propulsion of ships, pipeline compressors, and water pumps with ratings in the millions of watts. Electric motors may be classified by the source of electric power, by their internal construction, by their application, or by the type of motion they give.

The physical principle of production of mechanical force by the interactions of an electric current and a magnetic field was known as early as 1821. Electric motors of increasing efficiency were constructed throughout the 19th century, but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks.

Some devices convert electricity into motion but do not generate usable mechanical power as a primary objective and so are not generally referred to as electric motors. For example, magnetic solenoids and loudspeakers are usually described as actuators and transducers,^[1]respectively, instead of motors. Some electric motors are used to produce torque or force.^[2]