# ivestigate a factor that may affect the strength of an electormagnet

Topics: Magnetic field, Electromagnetism, Electromagnet Pages: 5 (1064 words) Published: October 23, 2013
The Strength of an Electromagnet

Introduction

I will be testing the factors which will make an electromagnet stronger. Electromagnets are magnets which are created and are easily controlled by electricity. All magnets have a region of space around them called the magnetic field which exerts a force on any magnetic material such as iron and steel or any other magnet which enters it. This force can be attractive and repulsive. If an electric current flows through a coil of wire a magnetic field is formed around the coil creating an electromagnet. This is a magnet which can be switched on and off.

To carry out this investigation I will follow the following steps: Insulated copper wire was coiled around a metal nail to make turns and then inserted into a power supply box. The coiled nail was put over a sheet of paper which had iron filings on, 6v was used and when the power was switched on the wire appeared to pick up the iron filings and this told us that an electromagnet was formed, because it was a short circuit the power supply switch of by itself and we had to reset it. As I stated before that the force can be attractive or repulsive in this case the force was attracted.

For our investigation we didn't use iron filings but we used a soft iron which was the nail, and the wire was wrapped around the core of the soft iron. We used 'soft' iron because soft iron loses its magnetism very quickly when the current stops and normal iron keeps its magnetism when the current stops. The magnetic strength can be increased significantly if the wire is wrapped around the core of the soft iron which forms a coil which is called a solenoid. The magnetic field of each single coil builds up to produce a stronger field around the solenoid. The solenoid behaves as a weak magnet; one side behaves as a north pole and one as a south pole. When current flows through the coil, the iron becomes magnetised. When the current is switched off the magnetic field collapses and the iron becomes demagnetised. This is the principle of an electromagnet. Electromagnets are 'multi - purpose' because they are so easily controlled and they are used in places like trains and circuit breakers. The strength of an electromagnet can be varied by: changing the number of coils of wire - the more coils, the stronger the magnet. More wire in one area means that the magnetic field is reinforced by other magnetic fields. A larger magnetic field is created (assuming that the current stays the same), and also by changing the current - the larger the current, the stronger the magnet (assuming the number of coils stays the same). The wire also has to remain the same because different wires could have different resistance. Presuming that the resistance of the wire stays the same then you have to change the voltage to change the current. Current changes in direct proportion to the voltage.

Hypothesis

I hypothesise that the variables that will change the strength of the electromagnet are the number of turns in the coil of wire. I also predict that the increase of current (voltage) will make the electromagnet stronger. The points I have made in my introduction back up my predictions.

To keep the wire variable the same I will use the same wire for each experiment, this keeps the resistant constant. The amount of current (voltage) will be easy to keep the same as you need a key to change the voltage in the power supply I will be using, when we need to change the voltage we will just have to call the teacher over and he will change it because there will be not enough keys to have one per group.

Plan

I am going to test how my variables will influence the strength of the electromagnet. My variables will be amount of turns on the coil and the amount of current. I will use power supply, wire, steel nail, paper with lines marked on keeping 2 mm distance apart and also we need a paper clip. This is how...