# Powering electromagnets question

• electrosiri
In summary: In that case one or more of the LEDs might be getting more than their fair share of current and could potentially start burning out.
electrosiri
So I'm trying to build some electromagnets and i have some questions regarding how to power them.

Imagine that i have a battery of 6 Volts and a coil with x gauge with y meters of wire that will equal 1 Ohm of resistance. So if i want to run it with 1 Amp of current i just put one 5 Ohm's resistor in series and i get the current i want. So far so good right?

Here's my confusion.

If instead of a coil i wanted to power leds that had foward voltage of let's say 2. I could only power 3 of them. No matter the current I am putting in (right?).

So in the coil case, instead of the 5 Ohm resistor what if i put 5 coils of 1 Ohm? i would still be running 1 Amp but instead i would be powering 6 coils instead of just 1 (?!) Isn't there something that limits the number coils i can use just like the LEDS case?

i think I'm missing something very basic here

thank you for your time, I'm still very new to electronics.

Hi electrosiri. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

Right.
Right.
The limit on the number of coils you can power in a series connection is limited by the wire resistance, as you point out.

Last edited by a moderator:
NascentOxygen said:
Hi electrosiri. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

Right.
Right.
The limit on the number of coils you can power in a series connection is limited by the wire resistance, as you point out.

So does that mean that i will save energy if i put them in series with no resistor, rather than putting them in parallel with a resistor?

I know there's probably some advantages of putting them in parallel. But just in terms of energy, seems like putting them all in series should save a lot of energy.

Ty for the quick answer.

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electrosiri said:
So does that mean that i will save energy if i put them in series with no resistor, rather than putting them in parallel with a resistor?
It sure does. That's assumng you are making use of those extra coils! If you are including them just for their resistance, then you'd be no better off. Whereever you have a resistor, or a resistance, it is turnng some of your electrical energy into heat. That's a loss in efficiency considerations.

Much the same applies to LEDs. If you look at LED strip lights they typically use groups of three LEDs in series with one resistor. They could use one resistor per LED but that would waste more power in the form of heat and would need more components.

Aside: electrosiri - In your example you proposed 3 x 2V LEDS operating from 6V. That wouldn't be recommended because the current wouldn't be well controlled. For example suppose when the LEDs were made they had a voltage of 1.9V instead of 2V. Three would have an operating voltage of 5.7V. To limit the current to 1A you would need a resistor with a value of R = (6-5.7)/1 = 0.3 Ohms. OK so far but what if the next batch of LEDs had a voltage of 1.8V? The current would be (6-5.4)/0.3 = 2A. eg a small variation in the LED forward voltage would change the current dramatically. For this reason you would be advised to use only 2 LEDs in series (4V) allowing 2V across a bigger resistor. There is a trade off to be made... On the one hand you don't want to waste power in the resistor but on the other hand you want the current and brightness to be well controlled so they all look the same. You might also like to consider what happens if the 6V power supply isn't exactly 6V? What if the battery was a bit flat and only delivering 5.5V?

## What is an electromagnet?

An electromagnet is a type of magnet that is created when an electric current flows through a wire, generating a magnetic field. Unlike permanent magnets, electromagnets can be turned on and off by controlling the flow of electricity.

## How does an electromagnet work?

An electromagnet works by using the principle of electromagnetism, which states that an electric current will produce a magnetic field around a wire. The strength of the magnetic field can be increased by increasing the amount of current or by adding more coils of wire.

## What are some practical uses of electromagnets?

Electromagnets have a wide range of practical applications, including in motors, generators, speakers, and MRI machines. They are also used in everyday devices such as doorbells, refrigerator magnets, and credit cards.

## How do you power an electromagnet?

To power an electromagnet, you need to connect the wire coil to a power source such as a battery or a power supply. The more power you provide, the stronger the magnetic field will be. It is important to use the correct voltage and amperage to avoid damaging the electromagnet.

## What factors affect the strength of an electromagnet?

The strength of an electromagnet is affected by several factors, including the number of coils in the wire, the amount of current flowing through the wire, and the type of core material used. A larger number of coils and a higher current will result in a stronger magnetic field, while using a ferromagnetic core material can also increase the strength of the electromagnet.

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