How to Make a Motor Video

The Many Types of North

[Untitled image of the Earth's poles]. Retrieved February 22, 2013, from:

     http://www.mnh.si.edu/earth/text/4_1_5_0.html

              Geographic north is based on the axis that the earth rotates around.  If we were to draw a line through the Earth that represents this axis, the point in the northern hemisphere where this line exits the Earth would be geographic north. This is also sometimes referred to as true north. All of our latitude and longitude lines are based off of the geographic north and south poles (DiSpezio, 2011).

EarthsMagneticField. Retrieved February 22, 2013, from:http://www.circulatethis.com/the-earths-magnetic-field-can-effect-more-than-just-your-compass-and-gps

              Magnetic north is determined by the Earth's magnetic field. This magnetic field is generated due to the liquid metal inside the Earth, the convection that takes place and the rotation of the Earth. Magnetic north is where the north end of a magnetic compass is attracted to. If you were to stand directly on top of the magnetic north pole, the compass would point straight down (Riddle, 2013). Since the opposite ends of magnets attract each other, the magnetic north pole is actually the Earth's physical south pole, and the magnetic south pole is the Earth's physical north pole. The magnetic field lines of the Earth move out from the pole in the southern hemisphere and into the pole in the northern hemisphere. Therefore when comparing to Earth to a bar magnet, the south pole is actually in the northern hemisphere as seen in the picture to above (Casselman, 2008).

                The geographic and magnetic poles are not in the same location, and the magnetic poles are constantly changing due to changes in the Earth. This difference can be determined through the use of magnetic declination or the degree of difference between the two poles (DiSpezio, 2011). 

References

(1) Casselman, A. (2008, February 28). Scientificamerican.com. Retrieved from                     

                    http://www.scientificamerican.com/article.cfm?id=the-earth-has-more-than-one-north-pole

(2) DiSpezio, M. A. (2011). Polar misunderstandings: Earth's dynamic dynamo. Science Scope, 35(2), 16-21.

(3) Riddle, B. (2013). Which way is north?. Science Scope, 36(5), 84-86.

The Energy Ball Report

Series and Parallel Circuits

                Series circuits and  parallel circuits are types of circuits. In a series circuit, there is only one path through which the electricity can pass. If this path is disrupted, any electrical devices that are connected would turn off. This disruption can be achieved using a switch or disconnecting a wire. In the energy ball lab, removing a finger from the metal conductor would open the circuit and stop the energy ball. Turning off a device can also cause a disruption (Henderson, n.d.). This is especially evident in things like older Christmas lights. If one light bulb burns out, then all of the light bulbs in the string will also turn off. It can be hard to determine where the problem is and it is therefore difficult to fix. A series circuit does however have its advantages as it can prevent an electrical  issue moving from one device to another since the current has been stopped. In a parallel circuit, there are multiple paths through which electricity could pass. As long as there is a closed circuit between a device and the power source, an open switch or broken device in another loop will not affect it . This type of circuit was created when we did the last activity with the whole class.  Houses are wired in parallel so that turning off the lights in a bedroom will not affect the lights in the kitchen.

Conductivity of the Human Body

                The human body is made up of covalent bonds and thus does not conduct electricity very well. However, the human body contains a lot of water with dissolved salts. Water has polar covalent bonds,  so pure water does not conduct electricity very well, but when salts are dissolved in water, it becomes a conductor. The body can then act like a wire and make the energy ball work. The brain needs salt to function, so if the ball does not work, a person must be dehydrated. Dehydrated, callused skin might not be able to make the energy ball work. The dry, dead skin cells can have a high resistance to electricity (Fish & Geddes, 2009).  The high resistance would mean that the skin no longer acts as a good conductor of electricity (Nave, n.d.) and the ball would not work in this case.

Self- Reflection

                I have learned that I have good collaboration skills and can work well in a group. During the lab, we discussed the answers and worked together to try and get the energy ball to work. At first we had some trouble finding metal to test our hypothesis for one of the questions, but eventually we were able to find some coins that we could use to test our answer. We, however, did not finish the whole lab, and could have improved on our time management by paying more attention to the clock and how many questions we had to answer. These time management skills are especially important to me because I get stressed when I don't think I have enough time to finish something.

Reference

(1) Fish, R. M. & Geddes, L.A. (2009, October 12). Conduction of electrical current to and through the   

                 human  body: A review. Retrieved February 3, 2013, from                  

                 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763825/

(2) Henderson, T. (n.d.). Two Types of Connections. Retrieved February 3, 2013, from

                http://www.physicsclassroom.com/Class/circuits/u9l4b.cfm

(3) Nave, C.R. (n.d.). Conductors and insulators. Retrieved February 3, 2013, from

                http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html