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Making Electro-magnetic Effects Visible

Traditional physics texts develop ideas and concepts in a hierarchical structure. Authors assume that the proper way to understand the subject is by working your way up through a web of ideas, from simple stuff at the bottom to higher concepts at the top. A serious defect in that approach to writing school-level physics is that by keeping it simple at the basic level we can also make it wrong. 1)

Electromagnetism is a branch of physics involving a type of physical interaction that occurs between electrically charged particles.

Electromagnetic fields include:

  • Electric fields
  • Magnetic fields
  • Light

Electromagnetism is one of the four fundamental interactions (commonly called forces) in nature. 2)

The interaction between electricity and magnetism (electro-magnetic effects are difficult to understand, to see, touch or otherwise experience at first-hand.

Contrary to our intuitive understanding about how things work in our everyday world, charged particles, such as electrons, move slowly through matter with a drift velocity of a snail (a fraction of a centimeter per second), but fields propagate at the speed of light (approximately 300 thousand kilometers in a second).

About much more than the delivery of electrical energy alone, the electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life.

Below, we present several projects using batteries, wires and magnets that demonstrate many basic concepts of magnetic machines in ways intended to make electro-magnetic effects more visible and better understood.

This section is not about Static Electricity, so lets get that out of the way right now:

John Travoltage


Video: Making Electromagnetic Effects Visible

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Static electricity used to be though of as something special, or different to ordinary electricity (current electricity), but this is not correct and becomes immensely confusing to new learners 3).

So what to do? simply avoid using the words “static electricity”. Instead, say “net charge” or “separated charge” or “the science of electrostatics”. Also, never say “current electricity”, instead say “charge flow” or “electric current”, or “the science of electrodynamics”. 4)


QUESTION: Why does a chair hold us up instead of just dropping us to the floor?

Video: Why? - Magnetism - Richard Feynman)

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ELECTRO-MAGNETIC MOTOR CHALLENGE

Video: Simple Rotational Motors (2min)

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Video: LPS Electric Motor Challenge (2min)

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THE LPS ELECTRIC MOTOR CHALLENGE (Read more...)


Simple solenoids (linear motors)

This section introduces is an example activity where students build a solenoid.

Solenoids appear practically everywhere, from car door locks to doorbells, from diskette drive ejectors to fuel injectors. The only difference is that most solenoids limit the range of travel, and usually have a spring return.

A solenoid is a coil wound into a tightly packed helix (spiral). In physics, a solenoid refers to a coil whose length is substantially greater than its diameter, often wrapped around a metallic core, which produces a uniform magnetic field when an electric current is passed through it. This type of solenoid is also an example of a simple linear motor.

A linear motor-style, electromechanical solenoid is:

  • Scalable to very large applications, possibly as large as a mass driver to put payloads into orbit. It's a keen space-age toy.
  • Has no moving parts – there's the magic of invisible forces at work.
  • Requires no special construction techniques or unusual tools.
  • Winding coils is fun and relaxing (at least for the first few!). Even small coils are remarkably powerful.

Fig. Solenoids - Electromagnet field for a simple coil:

Simple coil Simple Field


LPS MAGNETIC ROCKET CAR CHALLENGE

Each group must design an electro-magnetic coil and a touch switch to activate and power a magnetic rocket car.

The teacher will provide a standardised test system that includes all components EXCEPT the rocket power coil.

Each group will take turns to hand their own power coil to the teacher, who will add the coil to the test system to power a rocket car over a set course.

The coil that powers the test car for the greatest measured distance will win decide the winning group for this challenge.

Each winning group member will have the opportunity to be photographed wearing The Hat Of Power.

Video: Magnetic Rocket Car

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THE LPS MAGNETIC ROCKET CAR CHALLENGE (Read more...)



The LPS ADVANCED SINGLE WIRE MOTOR CHALLENGE (Read more...)



INVESTIGATE MAGNETIC FIELD IN A SLINKY (Read more...)


Ideas For Developing Deeper Understanding

References:

 
 
2018/electricity/electromagnetism/home.txt · Last modified: 25/06/2019/ 19:25 by 127.0.0.1