Physics Research Assignment - Solonoids

Leon

Summary of Investigation


An investigation was carried out to find out the relationship between the force created in a wire (or solenoid) when current flowed through it and the force from gravity. This was investigated by connecting a solenoid up to a variable power pack and then placing a light ring of either copper or aluminum around the solenoid. When the current flows through the solenoid, a magnetic force created from the solenoid should make the ring 'jump' up or levitate. When carrying out the experiment, the assumption was made that there will be some movement from the ring when current starts flowing through the solenoid and thus a magnetic field will be present. However, the results of the experiment did not back up this assumption in any way. No magnetic force was observed in any of the experiments carried out.


Introduction


Electromagnetism is the study of the relationships between magnetism, and electricity. It was found by Hans Oersted, that when an electric current flows in a wire, the current creates a magnetic force around this wire. It is also known that a solenoid produces a considerably large amount of magnetic force when a current flows through it (diagram 1.1 ). By using a solenoid and some small, light rings of copper and aluminum, it is said that the ring when placed over the solenoid when current is flowing will 'jump' up and sometimes levitate if the force of the magnetic field equals that of the earth's gravitational force.


Aim


The main objective of this experiment is to investigate the relationship between gravitational energy and electric and magnetic energy. This will be achieved by attempting to suspend a light ring of copper and/or aluminum around a solenoid with a current passing through it. The only presumption is that if the ring is unable to be levitated (due to lack of power), there will still be movement and the ring will jump up from the base of the solenoid.


Method


The circuit used first (see diagram 2.1) was made up of a small solenoid. The solenoid was constructed using a small pencil, bound with electrical tape and copper wire wound around it to a length of 13cm. Zinc plated washers were first used in the circuit using a DC voltage. Because DC voltage was being used, the ring was expected to 'jump' only when the circuit was switched on and off.


All voltages on the power supply were used and different resistances were experimented with using the rheostat. There were four washers tested, having radiuses of 9, 12, 18 and 21mm respectively.


A second attempt was made using the circuit in diagram 2.1 but AC power was used instead of DC. The reason for this is that if AC current is used, the flow of electrons will change rapidly and thus act like a DC switch begin turned on and off very quickly. A small key ring was substituted for the washer because of its lighter weighting.


It was found later that the washers being used were zinc plated but had iron in them so they were inappropriate for the experiment. After consulting a teacher, two small sheets of copper and aluminum were acquired and from these small sheets, rings where cut out and tested on the circuit shown in figure 2.1. The copper sheet was used first, cutting rings of radius 15, 20 and 25 mm and then placing them individually into the circuit for testing.


To increase the magnetic field, a secondary coil was round around the first one on the solenoid. Once again the copper rings were placed on the solenoid and test were carried out using AC and DC current. The aluminum sheet was then shaped into a ring of radius 40mm, and 65mm and experiments were carried out using these.


To increase the magnetic field a larger solenoid wound much more tightly was used. To add to the strength of the magnetic field a iron rod was placed in the middle of the solenoid. A number of resisters (390??, 100?? and 42??) were placed in the circuit to protect the solenoid for heating up too much. The circuit was set up as shown in diagram 2.2 using the aluminum, copper and aluminum foil rings. The aluminum foil was used because its mass was very small and also the aluminum and copper rings used so far had not backed up the hypothesis.


AC current was used