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Investigating the factors affecting the strength of an electromagnet.

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  • Investigating the factors affecting the strength of an electromagnet  
  • Background Knowledge:

The theory of magnetism is the only way to explain the process of magnetising an object. In an unmagnetised piece of iron the domains are pointing in numerous directions, which results in them cancelling each other out.

However, a magnetised piece of iron would have all the magnetic domains pointing in all the same direction. This is due to the north poles being at one end and the south poles at the other end. The domains are actually extremely small atomic magnets that line up with each other to form groups, called domains. All iron and steel are made up out of millions of these domains.

The magnetic field is the area around a magnet where it has a magnetic effect. The shape of a magnetic field can be determined by placing a thin layer of iron filings over paper with a bar magnet underneath. When the paper is gently tapped the iron filings act like tiny compasses and point themselves along the lines of flux. The magnetic field of an electromagnet is the same as a bar magnet and it looks like this:

Electricity has a magnetic effect; a wire carrying a current has a magnetic field round it.

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Due to my background knowledge I predict that with the increase in the number of coils, the electromagnet will become stronger. This is because every turn of coil has its own magnetic field. When there are more turns in the same area, the coils magnetic fields overlap and this creates a stronger force.

The increase in current put into the electromagnet will increase its force also. This is because as more power is introduced to each coil, its magnetic field is increased and strengthened, causing the magnetic field to extend its previous limits and be able to attract more paperclips.

  • Results:

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  • Evaluation:

The experiment I chose in my investigation was a good method to use as it effectively illustrated my prediction and was fairly simple to construct and carry out.

The results were very accurate and I had no anomalies, I think this was because I was very careful in trying to maintain one variable only and keeping all other factors constant by using, for instance, an ammeter to observe the current in a lot of accuracy.

The method may not have been entirely accurate as I am not sure that using paperclips to ascertain the electromagnets strength was the most accurate method, this is because it is hard to attach the paperclips once they have reached a certain length although this could have been because the magnetic field only reached so far. I am not sure how the method could be improved to gain more accurate results although possibly using a different material would be advisable.

Despite these queries I am certain that my results firmly support my conclusion as they match up with my background knowledge, prediction and follow a very clear pattern.

Further work could include varying the core used in constructing the electromagnet; I could investigate what makes the electromagnet stronger and weaker in the form of core material.

Lucy Gould                25th February 2002

Mr Wynne, Physics

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