Magnetism lab Passing it on Magnetism is the force exerted by magnets when they attract or repel each other. Magnetism is caused by the motion of electric charges. Every substance is made up of tiny units called atoms. Each atom has electrons, particles that carry electric charges. Spinning like tops, the electrons circle the nucleus, or core, of an atom. Their movement generates an electric current and causes each electron to act like a microscopic magnet. In most substances, equal numbers of electrons spin in opposite directions, which cancels out their magnetism. That is why materials such as cloth or paper are said to be weakly magnetic. In substances such as iron, cobalt, and nickel, most of the electrons spin in the same direction. This makes the atoms in these substances strongly magnetic—but they are not yet magnets. To become magnetized, another strongly magnetic substance must enter the magnetic field of an existing magnet. The magnetic field is the area around a magnet that has magnetic force. All magnets have north and south poles. Opposite poles are attracted to each other, while the same poles repel each other. When you rub a piece of iron along a magnet, the north-seeking poles of the atoms in the iron line up in the same direction. The force generated by the aligned atoms creates a magnetic field. The piece of iron has become a magnet. Some substances can be magnetized by an electric current. When electricity runs through a coil of wire, it produces a magnetic field. The field around the coil will disappear, however, as soon as the electric current is turned off. The image on the right shows the atomic alignment of non-magnetic material and the left shows the atomic arrangement of material that is a magnet. Procedures: 1. Take two nails and see if you can feel any magnetic attraction between them. Will a nail pick up a paper clip by touching it? 2. Place a magnet on one end of a nail. Touch the other end of the nail with a second nail. Do you feel a magnetic attraction between the two? 3. Keeping the magnet touching the nail, can you pick up paper clips by touching them with the other end of the nail? 4. What does this tell you about the atomic arrangement of the metals both before touching the magnet and after? Beach sand Titanium orr has been found on the coast of the coastal plains in Georgia and Virginia. Often it can be seen on the beaches as black lines that form in low places that the waves create as seen above. Since it is a heavy metal hit resists being washed away by slow moving waters and is easily seen. This has led some to call for mining off the coast of Georgia to increase the supply for domestic industry. The coast of Georgia is also known for its rich marshlands that lead to the waters being so nutrient rich and the seafood so abundant. The organic matter that feeds this ecosystem is also very dark in nature. The goal is to determine if the dark matter in the beach sand is organic matter like decaying leaves that turn dark or titanium metal. Procedures; 1. Take the small container of beach sand and add water. Organic matter should float. If the dark substance in the sand does not float or dissolve it probably is not organic in nature but it could be dark rock mineral rather than metal. 2. Next pour off the standing water in the container. 3. Once you can get to the sand (even though it is wet) see if the magnet can pick up the dark matter. What does that tell you about its composition? Discovering the invisible Magnetic fields may be represented by continuous lines of force or magnetic flux that emerge from north-seeking magnetic poles and enter south-seeking magnetic poles. The density of the lines indicates the magnitude of the magnetic field. At the poles of a magnet, for example, where the magnetic field is strong, the field lines are crowded together, or more dense. Farther away, where the magnetic field is weak, they fan out, becoming less dense. A uniform magnetic field is represented by equally spaced parallel straight lines. The direction of the flux is the direction in which the north-seeking pole of a small magnet points. The lines of flux are continuous, forming closed loops. The images above show the field lines or magnetic flux lines of a magnet. Your job is to determine if the images are accurate. Procedures; 1. Take two of the magnets, turn the poles to where they repel each other and get a feel for the area that pushes away. What shape is the area that you can feel? Do you think the area of attraction would look the same way? Why or why not? 2. Take the paper tray and have the teacher come and put a bit of iron filings in the tray. Use a magnet to put under the paper tray. Does the iron filings line up the way you thought they would? Create (or find) a drawing or image of what you saw Which way did it go? Is the Earth a magnet? In a sense, yes. The Earth is composed of layers having different chemical compositions and different physical properties. The crust of the Earth has some permanent magnetization, and the Earth’s core generates its own magnetic field, sustaining the main part of the field we measure at the surface. So we could say that the Earth is, therefore, a "magnet." True north is a fixed point on the globe. Magnetic north is quite different. Magnetic north is the direction that a compass needle points to as it aligns with the Earth’s magnetic field. What is interesting is that the magnetic North Pole shifts and changes over time in response to changes in the Earth’s magnetic core. It is not a fixed point. A compass works by detecting and responding to the Earth’s natural magnetic fields. The Earth has an iron core that is part liquid and part solid crystal, due to gravitational pressure. It is believed that movement in the liquid outer core is what produces the Earth’s magnetic field. Like all such fields, the Earth’s magnetic field has two poles - north and south. These magnetic poles are slightly off from the Earth’s axis of rotation, which is used as the basis of the geographic poles - however the magnetic and geographic poles are close enough to allow a compass to serve as a valuable navigation tool An orienteering compass typically consists of three main parts: a magnetic needle, a revolving compass housing, and a transparent base plate. The magnetic needles north end is painted red and its south end white. The housing is marked with the four cardinal points of north, east, south, and west. Directions; 1. Which way do magnets normally align when they are brought to another magnet? Will the north pole point to the other magnet’s north or south pole? 2. If a compass is a magnet and the north pole points a certain direction what is it pointing to? 3. Is there anything else that can make a compass point in a certain direction? a. Take a compass and bring one of the magnets close. What do you notice? Turn the magnet around, what do you see then? b. Is there anything else that can make a compass point the wrong direction? That’s a bit of a shock… Voltage detectors do not actually detect voltage, but instead electric fields. Electric fields are created by voltage and the two have a causal relationship, which means that the higher the voltage, the greater the electric field. Magnetic fields are created by the current and have the same relationship as electric fields and voltage.The internal circuit of a non-contact voltage detector leads to a sensor which is positioned in the tip of the tool. When the electromagnetic waves hit the sensor a signal is sent through the circuit which turns on the light and/or buzzer. We have often said there is a relationship between electrical fields and magnetic fields. Lets see if that is true. 1. Request a voltage detector for a teacher. 2. Touch some things to the detector to see if it sets it off like a pen, nail, table leg or whatever comes to mind. 3. Try touching the detector to a magnet. What happened? Turn the magnet over, does it do the same thing? What is going on with this?
