Eddy Current Brake

A spinning copper disc is slowed down when a magnet is brought near it. Note that copper is not a magnetic material. Eddy currents are induced in the disc due to the relative motion of the disc and the magnet. The magnetic fields associated with these currents have such a direction that they oppose the cause that created them in the first place (Lenz rule). As a result they oppose the relative motion between the disc and the magnet and hence the disc is slowed down.

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Eddy Current Brake from Horatiu Pop on Vimeo.

Applications of electromagnetic induction

Crank flashlight and other applications of electromagnetic induction.

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Variation of the electric current in a DC motor

The current drawn by a simple motor may vary in time depending on what the motor does at any given instant.

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Quick Demo: Variation of the electric current in a DC motor from Horatiu Pop on Vimeo.

Motor Effect

When placed in a magnetic field, a current carrying conductor experiences a force.

Source:  Horatiu Pop

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Electromagnetic induction

A changing magnetic flux induces a current into a coil.

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IBPH Episode #9 - Electromagnetic induction

This episode is an introduction to electromagnetic induction. The presentation is supported by many experimental demonstrations.

The video covers the following topics: 1. Oersted’s discovery of the magnetic effect of an electric current (sometimes called the “motor effect” as it is the principle behind simple DC motors); 2. Faraday’s discovery of electromagnetic induction; 3. Magnetic flux; 4. Flux linkage; 5. Faraday’s law of electromagnetic induction; 6. Lenz’s law (or Lenz’s rule); 7. Eddy currents and their braking effect.

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IBPH Episode #9 - Electromagnetic induction from Horatiu Pop on Vimeo.

IBPH Episode #8 - Simple Harmonic Motion (Part 2)

This is the second video on "Simple Harmonic Motion" (SHM)
Topics covered in this episode: (a) The period of a gravitational pendulum (b) Using a gravitational pendulum to determine the acceleration due to gravity, g, (c) Measuring mass using harmonic oscillators, (d) Energy in SHM, (e) Connection between SHM and uniform circular motion.

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IBPH Episode #7 - Simple Harmonic Motion (Part 1)

Simple harmonic motion (SHM) is a type of periodic motion for which the force that drives it is proportional to the displacement from the equilibrium position. What is the equation that describes this type of motion? The answer and more in this video.

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IBPH Episode #7 - Simple Harmonic Motion (Part 1) from Horatiu Pop on Vimeo.

IBPH Episode #6 - Graphs of Motion

What is the purpose of plotting various graphs for moving bodies? How are quantities like displacement, velocity and acceleration calculated from graphs of motion? This podcast covers the three main types of graphs: displacement-time, velocity-time and acceleration-time graphs.

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IBPH Episode #5 - Uniform Motion

The topic of this episode is Uniform Motion. What is an equation of motion? How does the equation of motion look like in the specific case of uniform motion? How do we use equations of motion in solving problems? The answers, with examples, in this episode.

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IBPH Episode #5 - Uniform Motion from Horatiu Pop on Vimeo.

IBPH Episode #4 - Types of Motion

Uniform motion, uniformly accelerated motion, uniform circular motion, simple harmonic motion - what is the difference between all these types of motion? This episode covers the most common types of motion one may come across while studying physics in high school.

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IBPH Episode #4 - Types of Motion from Horatiu Pop on Vimeo.

IBPH Episode #3 - Describing Motion: Speed, Velocity and Acceleration

If you want to describe the motion of a moving body, you have at hand three important physical quantities: speed, velocity and acceleration. How is each one of them defined? What's the difference between average and instantaneous velocity? The answers and more in this third episode.

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IBPH Episode #3 - Describing Motion: Speed, Velocity and Acceleration from Horatiu Pop on Vimeo.

IBPH Episode #2 - Working with Vectors

The topics covered in this second episode are: displacement, vector addition, vector subtraction, products of vectors, components of a vector.

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IBPH Episode #2 - Working with Vectors from Horatiu Pop on Vimeo.

IBPH Episode #1 - Physical Quantities. Scalars and Vectors

Physical quantities, units, scalars and vectors.

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