Savannah, Javier, Donovan, Amelia Electric Current Savannah, Javier, Donovan, Amelia

Background Information Electric currents were not fully investigated until batteries were invented in about 1800. Passing currents through salt solutions provides evidence that there are two kinds of charge carriers, positive and negative. The charge carriers that boil out of white hot metals are negative electrons, and movements of electrons produce current in a cool, metal wire. For a time electric currents seemed so different from electric charges at rest that the two were studied separately. It seemed as if there were four kinds of electricity: positive and negative electrostatic charges, and positive and negative moving charges in currents. Now scientists know better. There are just two kinds, positive and negative, exerting the same kind of forces whether they were electrostatic charges from friction or moving charges from power supplies.

Question or Hypothesis Can we demonstrate electric currents using electromagnetism? I hypothesize that we can demonstrate electric currents with a magnet and prove it with a galvanometer.

General Information/How to Conduct Experiment A galvanometer is used to detect if there are any electrical currents in the area of which it is attached to. If we hook the galvanometer up to a coil of copper wire, then push the magnet into the coil, the dial on the galvanometer should move to the right, and as we pull it out to the left.

Materials Needed 1. Galvanometer 2. Wire coil 3. Magnet

Step by Step Instruction 1. Attach the galvanometer wires to the end of the wire coil 2. Push the magnet slowly through the center of the coil and watch as the dial moves 3. Pull the magnet slowly out and watch as the dial reverses its direction

Explanation of Calculations When you push the magnet in it creates direct current and when you pull it out it creates alternating current

Analysis of Results As we can see here, the galvanometer is detecting a electic current due to the fact that a magnetic field is being introduced.

Conclusion Supported by Evidence In conclusion, the electric current was detected because the flow of the magnetic field going from its north pole to south pole created a charge on this wire. Also copper wire is know as a conducting wire due to the fact that it readily accepts electrons.

Evaluation of Hypothesis Our hypothesis can be proved true because the galvanometer showed that an electric current was introduced.

State and Explain Major Concepts Electric currents describes the flow of electrical charge, or the flow of electrons along a wire or ions in an electrolyte. One important thing is that the wire must be connected to a circuit to carry electric charge. The SI unit for measuring an electric current is called the ampere, and is the flow of a charge across a surface at the rate of one coulomb per second. It is measured with an ammeter.

Historical Perspective Humans have only harnessed the power of electric currents for roughly 250 years, though we have known about them for much longer. A turning point in the use of electric currents was in 1831 by Michael Faraday,, who used the concept of electromagnetic induction to create an electric current in a coil.

App of Concepts Electricity is used all around us today, from the handheld devices that we love so much to the lights we use to see.

Think and Explain 1. Different quantities; the potential difference (or voltage) causes a flow of charge, which is the current. 2. 2 Amperes. 3. Voltage is the change in energy per Coulomb of charge. V = U/q The amount of energy gained must have came from the work done by the battery. 1029Watts 4. 8 volts 5. Current remains the same in both cases. 6. 0.005 amps 7. Due to the wires having electrical resistance, which means that the resist the motion of electrons, the electrons bump into atoms on the outside of the wire, and some of their kinetic energy is given to the atoms as thermal energy. This thermal energy causes the wire to heat up. 8. Thick wires have less electrical resistance and will carry greater amounts of current without overheating. 9. The electrical system in a car is powered by a battery so it is DC; electricity in a home is powered by an alternating current generator so it is AC. 10. If the bulb were connected to a 120 volt circuit it would have 2 amperes, and 4 if it were to have 240 volts. 11. 10 amps 12. 12 v/amps

Review Questions 1. Temperature Difference; Voltage Difference 2. Potential energy/charge; Change in Potential Energy/charge between points 3. Pressure Difference (voltage); Potential Difference 4. Flow of charge 5. Flow of 1 charge/1 second 6. The potential energy per coulomb of charge available to electrons that move from one terminal to the other equals the potential difference (voltage) that provides the “electrical pressure”. 7. 120 Joules 8. Through 9. Across 10. That which resists flow of charge (measured in ohms) 11. Greater in a long, thin wire 12. Current = voltage/resistance, or I =V/R 13. It drops to half

Review Questions 15. Lowers skin resistance 16. Water is a conductor. Distilled water can be a good insulator but ordinary water is not. 17. Negligible potential difference across the body 18. Serves as a ground connection 19. DC--current flows in one direction; AC--direction alternates; DC is produced by a battery, AC by a generator. 20. It is the electric field that travels through a circuit at the speed of light. 21. DC--less than 1 cm/s; AC--zero 22. From the conductors themselves 23. P = energy/time, rate of doing work 24. Power--watt, kilowatt; energy--kilowatt-hour 25. 0.5 amps