25 Electromagnetic Induction

This page covers the EM Induction section of the course.  It is really key again you learn the definition slides I have put  here and revisit them over and over. They will eventually make sense but it takes a lot of recap to be sure.

Resources

25 Electromagnetic Induction

25 EM Induction Student Booklet

11. Induced EMF DP

AQA Worked Answers for Practice

IOP Electromagnetism Slides

https://phet.colorado.edu/en/simulation/faradays-law

Magnetic Induction - Generators

Super simple idea to show how magnetic fields can interact and push electrons around a wire. This is an electrical current.

Motion depends on Magnetic field direction, strength and speed of ...movement.Show More

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Magnetic Induction - Generators

Super simple idea to show how magnetic fields can interact and push electrons around a wire. This is an electrical current.

Motion depends on Magnetic field direction, strength and speed of ...movement.Show More

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GCSE Physics - Generator Effect / Electromagnetic Induction (2026/27 exams)

⭐️ Check out our website https://www.cognito.org/ ⭐️

*** WHAT'S COVERED ***
1. The Generator Effect (Electromagnetic Induction).
2. Generating Current.
* Inducing potential difference/current by moving the magnet instead of ...the conductor.
* Conditions where no potential difference is induced.
3. Factors Affecting Induced Potential Difference/Current.
4. Induction in a Coil.
* Moving a magnet into or out of a coil induces potential difference and current.

*** EXAM BOARD INFO ***
AQA - Separate/triple science and higher tier only
IGCSE Edexcel - Everything is relevant to your course
Edexcel - Separate/triple science and higher tier only
OCR 21st Century - Separate/triple science only
OCR Gateway - Separate/triple science and higher tier only

*** CHAPTERS ***
0:00 Intro to the Generator Effect (Electromagnetic Induction)
0:21 Inducing Potential Difference in a Wire
0:40 Requirement for Motion (Change in Magnetic Field)
1:08 Effect of Changing Direction of Motion
1:21 Inducing Current in a Circuit
1:48 Moving the Magnet Instead of the Wire
2:08 When No Potential Difference is Induced
2:26 Factors Affecting the Size of Induced Potential Difference
2:39 Factor 1: Magnetic Field Strength
2:50 Factor 2: Speed of Movement
3:03 Factor 3: Number of Turns in a Coil
3:18 Summary of Induction Principles
3:40 Summary of Factors Increasing Induced Current
3:59 Induction with a Coil and Bar Magnet
4:22 Reversing Current Direction with Coil/Magnet

*** PLAYLISTS ***
https://youtube.com/playlist?list=PLidqqIGKox7XPh1QacLRiKto_UlnRIEVh&si=orIUwL3o2jOoiYjT

https://youtube.com/playlist?list=PLidqqIGKox7X5UFT-expKIuR-i-BN3Q1g&si=DcihOwUkd9oWbbdp

https://youtube.com/playlist?list=PLidqqIGKox7WeOKVGHxcd69kKqtwrKl8W&si=Y8MsO-FK948jnxpS

https://youtube.com/playlist?list=PLidqqIGKox7UVC-8WC9djoeBzwxPeXph7&si=-7i5Iq7yOeJrhtu6

https://youtube.com/playlist?list=PLidqqIGKox7VKJD2WxRhoKaI6JGLVean8&si=NH_Q1ujhVgACM2FU

#GCSE #Physics #study #revision #school #exam #AQA #OCR #Edexcel #IGCSE #IB #APShow More

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Physics hand rules explained

When dealing with electromagnetism, there are a number of hand rules, to make sense of the directions of the various dimensions.
This video makes sense of all those rules


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Physics High is committed to producing content that teaches physics concepts at a level a high schooler can understand.Show More

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Commutators: Basics on AC and DC Generation

Basics of electricity: how generators make AC power, how to make DC power using a commutator.

This video is integrated as part of our Generators Page:
http://www.EdisonTechCenter.org/generators.html

Now Playing

GCSE Physics - How Transformers Work (2026/27 exams)

⭐️ Check out our website https://www.cognito.org/ ⭐️

*** WHAT'S COVERED ***
1. The role of transformers in the National Grid.
* Using step-up transformers.
... * Using step-down transformers.
2. The basic structure of a transformer.
* Primary coil, secondary coil and iron core.
3. The process of electromagnetic induction in a transformer.
4. How transformers change voltage.
* The relationship between the number of turns on the primary and secondary coils.
* How step-up transformers increase voltage.
* How step-down transformers decrease voltage.

*** EXAM BOARD INFO ***
AQA - Separate/triple science and higher tier only
IGCSE Edexcel - Separate/triple science and higher tier only
Edexcel - Higher tier only
OCR 21st Century - Separate/triple science and higher tier only
OCR Gateway - Separate/triple science and higher tier only

*** CHAPTERS ***
0:00 Intro & Role in National Grid
1:07 Transformer Structure
1:24 How Transformers Work (Step-by-Step)
3:21 Changing the Voltage (Step-up vs Step-down)

*** PLAYLISTS ***
https://youtube.com/playlist?list=PLidqqIGKox7XPh1QacLRiKto_UlnRIEVh&si=orIUwL3o2jOoiYjT

https://youtube.com/playlist?list=PLidqqIGKox7X5UFT-expKIuR-i-BN3Q1g&si=DcihOwUkd9oWbbdp

https://youtube.com/playlist?list=PLidqqIGKox7WeOKVGHxcd69kKqtwrKl8W&si=Y8MsO-FK948jnxpS

https://youtube.com/playlist?list=PLidqqIGKox7UVC-8WC9djoeBzwxPeXph7&si=-7i5Iq7yOeJrhtu6

https://youtube.com/playlist?list=PLidqqIGKox7VKJD2WxRhoKaI6JGLVean8&si=NH_Q1ujhVgACM2FU

#GCSE #Physics #study #revision #school #exam #AQA #OCR #Edexcel #IGCSE #IB #APShow More

Now Playing

Faradays Law - Back EMF Eddy Currents Video 1

This is such a cool demonstration of induction

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Motor Effect

Simple demonstration of the Motor Effect or FBI Flemings Lefthand rule.

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Six Experiments That Changed the World - Faraday and the Doughnut - Part 1 of 3

Excellent Science video about my science hero Michael Faraday. No copyright breach intented. Uploaded for Educational Purposes only.

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Six Experiments That Changed the World - Faraday and the Doughnut - Part 2 of 3

Excellent Science video about my science hero Michael Faraday. No copyright breach intented. Uploaded for Educational Purposes only.

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Six Experiments That Changed the World - Faraday and the Doughnut - Part 3 of 3

Excellent Science video about my science hero Michael Faraday. No copyright breach intented. Uploaded for Educational Purposes only.

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Regenerative Braking - Explained

What is regenerative braking? How do electric cars and hybrid cars regenerate power through braking? How does regenerative braking work? Regenerative braking is a fairly easy to understand concept, once ...one understands how motors work, and how generators work. Regenerative braking translates to energy savings, as it recovers kinetic energy. A motor can simply be reversed in order to generate electricity, acting as a generator to recharge a vehicle's battery pack.

-- Related Videos --
Alternating Currents: http://youtu.be/Pv8WxPsJf4A
KERS: http://youtu.be/QibB4DxkasQ
Electric Cars: http://youtu.be/MWcmUgKP1GU

-- Other Useful Videos --
Electric Motors: http://youtu.be/ErV5lGVso1w
Magnets: http://youtu.be/7nhmJPMi4FU
Electromagnets: http://youtu.be/1YSjRrijsRg
DC Motors: http://youtu.be/kTkqbcesf10

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NEW VIDEO EVERY WEDNESDAY!Show More

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Counter EMF and motor current/speed

In this video I try to explain what CEMF is, how it limits DC motor current, and why CEMF determines at what speed a DC motor will run at

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Alternating Current v Direct Current GCSE

This is a simple video to show electrical current with an AC and then DC source. You can see how the alternating current is a wave which has a frequency ...of 50Hz and direct current is just steady.Show More

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Alternating Current vs Direct Current - Rms Voltage, Peak Current & Average Power of AC Circuits

This physics video tutorial provides a basic introduction into the difference between alternating current vs direct current. It explains how to calculate the rms voltage and rms current in ...an AC circuit as well as the peak voltage and peak current. In addition, it explains how to calculate the average power in an AC circuit. This video contains plenty of examples and practice problems.

Physics Video Lessons:
https://www.video-tutor.net/physics.html

Final Exam and Test Prep Videos:
https://bit.ly/41WNmI9

___________________________
Electric Current in Circuits:
https://www.youtube.com/watch?v=r-SCyD7f_zI

The Electric Battery:
https://www.youtube.com/watch?v=xrf6I_5vX64

Ohm's Law Problems:
https://www.youtube.com/watch?v=NxxNu9Cek1E

Resistance and Resistivity:
https://www.youtube.com/watch?v=PIJTu8z0-_U

Resistor Color Code:
https://www.youtube.com/watch?v=G1mZutobxDU

______________________________
Internal Resistance of a Battery:
https://www.youtube.com/watch?v=R1QN_0fcZ_8

Electromotive Force of a Battery:
https://www.youtube.com/watch?v=k077CwKGiwk

Drift Velocity and Current Density:
https://www.youtube.com/watch?v=KiTkSZy79cw

Potential Difference Between Two Points:
https://www.youtube.com/watch?v=vcbkvYDP5a8

______________________________
Schematic Diagrams & Symbols:
https://www.youtube.com/watch?v=Dl1gFBNa0Ik

Open, Closed, and Short Circuits:
https://www.youtube.com/watch?v=v5RJf_V0LYA

Resistors In Series:
https://www.youtube.com/watch?v=9z53qVQjasU

Resistors In Parallel:
https://www.youtube.com/watch?v=SYrOiQs3X2U

Physics PDF Worksheets:
https://www.video-tutor.net/physics-basic-introduction.htmlShow More

Now Playing

Transformer Melting a Nail - Very Dangerous

This video is a bit of fun. If you take a 13A 230V primary connection on 800 turns and reduce N to just 5 turns the current increase is to ...about 2000A.

This means the nail will be extremely dangerous to touch and this would kill you. So take care!

If you use the transformer equation then the power equations you can work out the output current assuming 100% transfer.

Vp/Vs = Np/Ns

Pp = IpVp

Ps = IsVsShow More

Now Playing

Powerlines and Transformers iGCSE Physics

This quick setup shows how energy is lost when current flows in a wire such a power cable.

Using transformers we can step up the PD and reduce current flow ...I. This means that since...

Ploss= I*I*R. The reduction in lost energy is useful as the current is much reduced.

Take care though these cables have a PD of 160V which is very high and dangerous. NEVER touch the cable when it is on.Show More

Now Playing

How Transformers Work - AQA A Level Physics

This is an upload from a video that has gone from youtube, if it is yours please put it back up. I claim no copyright for this, but it is ...very useful

ThanksShow More

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Faradays Law - Back EMF Eddy Currents Video 2 - AQA A Level Physics

This is such a cool demonstration of induction and shows faradays law of induction.

The relationship between changing magnetic flux and induced electromotive force  (epsilon) is known as Faraday's law ...of electromagnetic induction:

The magnitude of an electromagnetic force induced in a circuit is proportional to the rate of change of the magnetic flux linkage that cuts across the circuit.

Induced voltage E is determined by two factors:

1) The amount of magnetic flux

2) The rate at which the magnetic field lines cut across the conductor

NB: The induced EMF acts as such to oppose the change that causes it (see details on previous) slide.Show More

Now Playing

Faradays Law - Back EMF Eddy Currents Video 1

This is such a cool demonstration of induction

Now Playing

Faraday's Law of Electromagnetic Induction and Eddy Currents - AQA A Level Physics

Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of ...a conductor in a magnetic field. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an AC electromagnet or transformer, for example, or by relative motion between a magnet and a nearby conductor. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material.

By Lenz's law, an eddy current creates a magnetic field that opposes the change in the magnetic field that created it, and thus eddy currents react back on the source of the magnetic field. For example, a nearby conductive surface will exert a drag force on a moving magnet that opposes its motion, due to eddy currents induced in the surface by the moving magnetic field. This effect is employed in eddy current brakes which are used to stop rotating power tools quickly when they are turned off. The current flowing through the resistance of the conductor also dissipates energy as heat in the material.

In this case the strong Neo magnet induces an electrical current to flow in the non-magnetic aluminium ring. The movement of the current creates a Magnetic field which opposes the magnetic field which created it, thus causing a force to act on the aluminium mass.

Hence, it turns!

When you have a split ring, no eddy current can form and thus there is no magnetic effect.Show More

Now Playing

Faraday's Donut Experiment - AQA A Level Physics

Micheal Faraday did this as a the precursor to the first electric motor.

Amazing and changed the world.

Now Playing

Sparking Power lines and Mist in Derbyshire

Power lines will leak charge on a misty day. This is why you can heat the discharge.

Also note it is due to the High tension of the lines or ...high PD.

Powerloss is due to the power equation...

Ploss = I^2 x R

So less current means least wasted energy.Show More

Now Playing

Lenz’s Law - Magnet in Helmholtz Coil - Vernier Data Logger

A Magnet inserted into a solenoid creates a current flow which creates a field which opposes the direction of motion. (conservation of energy!)

Thus a N-pole inserted into a coil ...creates a...

“North pole - aNticlockwise” current flow. (see Fig 2a page 413)

Rule to learn is.....

North pole - aNticlockwise

South pole – Clockwise

A rapidly changing magnetic field induces electric currents to flow in a closed circuit. A bar magnet is dropped vertically through a coil linked to a centre-zero galvanometer.

A graph of coil EMF against time shows that: When the first pole(S) falls through the coil EMF increases to a level then decreases.

When an emf (current) is generated by a change in magnetic flux according to Faraday's Law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it.

The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant.

When the middle of the magnet falls through the coil, the EMF is at a minimum.

Maximum EMF is obtained when the second pole(N) falls through the coil. This is when the rate of cutting lines of force is highest, because the magnet is falling faster. As a result of the velocity being greater the period of high EMF is shorter.

Note that because the field direction is reversed when the poles drop through the coil, the induced current direction is also reversed. So the EMF is reversed (EMF is directly proportional to current).Show More

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Magic Sound via Air Gap #shorts

The signal generator produces an alternating current through one coil of wire. The half c-core has a better permeability that air to allow a magnetic field to be induced. This ...field matches the ac current. The field causes a secondary magnetic field to be induced in the other half c-core which in turn creates an AC current in the secondary coil.

The signal is transferred to an amplifier and the sound wave is transferred through the air as if by magicShow More

Now Playing

Lenz's Law - LED Diode - Induction

Lenz's law, in electromagnetism, states that an induced electric current flows in a direction such that the current opposes the change that induced it. This law was deduced in 1834 ...by the Russian physicist Heinrich Friedrich Emil Lenz (1804–65). Lenz's law indicates the direction of the induced current.

A potential difference in this case is produced when a magnet moves into a coil of wire. This process is called electromagnetic induction. The direction of the induced voltage is reversed when the magnet is moved out of the coil again. It can also be reversed if the other pole of the magnet is moved into the coil. So in this case the coil is clearly short and the magnet cannot move out of the coil so the potential difference, seen by the current flowing in the diode (it lights) only is shown in one direction. When you turn the polarity around of the magnet it will not produce the current as a diode blocks the current.Show More