How Transformers Work

A brief video detailing the key points regarding the operation of electrical transformers. The video discusses electromagnetism, induction and the transformer formula.

This is aimed at UK GCSE students (age 15-16), though A-level candidates may benefit viewing it as refresher when studying electromagnetic machines.


Apologies if you watched the whole video waiting for something to turn into a robot.

Category:

Education

Tags:

• Transformer
• electricity
• step-up
• step-down
• inductor
• electromagnetism
• induction

[Krazyness]

I feel like there is an error in this video. For the dots with the "+" indicating current going away from you, shouldnt the magnetic field be revolving COUNTER clockwise? using the left hand rule, would show that

[t33chin]

@Krazyness You are getting your hands mixed up. For understanding the direction of a magnetic field in a wire, it is best to think of the 'corkscrew' or 'thread' rule. When you screw in a regular corkscrew, as the corkscrew turns clockwise, it moves away from you (inwards). You are thinking of the right hand rule.

Fleming's left hand rule is usually used for the 'motor effect' (3 fingers sticking out). This is to understand the Lorentz force in magnetic/electric fields.

[16f8771]

If a air core copper coil gives a magnetic field then why is there no north/south pole developed and the "magnetic field" will not attract metal?

[t33chin]

@16f8771 There IS a magnetic field, with poles. Due to the poor permeability of air (which is pretty much the same as a vacuum), the magnetic field will be very weak (to us). The iron core is much more permeable due to domain alignment as in my 'domains' video.

[TheLionRichard]

You need a very balanced AC current (mix of positive and negative current) to make a transformer work properly then? So you get a moving/alternating/fluctuating magnetic field to create the output current.

[t33chin]

@TheLionRichard Ideally a pure sine wave. A fourier analysis of any other waveform will reveal that it is simply a summation of multiple waves at differing frequencies and amplitudes. It is hard to make a transformer with perfectly linear behaviour under these conditions.

[t33chin]

@LOPEZdJUNGLIST Yes, and it was very hard to get off.

[foxjackalwolf]

superb dude, you explained everything so easily. I understood it good. thanks

[NoSpoonForYou]

But where is the energon?

[kolokoy389]

it could be haven this injunction from LCD Backlight inverter 24 volts primary into kilo volts secondary.. switching flow of current by two mosfet IRF3205 in primary circuit of inverter.

i am Electronic technician from the Philippines,

[powermaks]

you forgot to explan about the amperage!!!

[powermaks]

if its the ratio that makes the difference, than why dont transformers use one winding ond the pimary and a few hundred on the secondary to get 1000V?

[lethalmicky13]

Really great video thank you. Could you do some on generators and motors please if you have time.

[jones3700]

explained very well.

[shinjikenny]

5:44 Is the direction of winding important? What if the second winding is wound in clockwise direction from left to right (same as how the first winding is done)?

[TheCrazyStudent]

(previous post got cut in the middle)

*... what the best number of turns would be for a given application?

Thanks.

[TheCrazyStudent]

I have a question. Take two transformers, one with a primary of 2000 turns and a secondary with 1000 turns, and a second transformer with a primary of 100 turns and a secondary of 50 turns. If both are fed with the same voltage in the same AC frequency, what would be the difference between the two? They both have the same ratio. In other words, if the ratio (and not the nr of turns) is determining the output voltage, how do I figure out what the best suitable nr of turns would be for a given ap