pre-lab preparation sheet for lab 4—batteries, bulbs, and current

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there is a conducting material connected between its terminals. If this conductor happens to be the filament in a small light bulb, the flow of charge will cause the light bulb to glow. *Some activities in this lab have been adapted from those designed by the Physics Education Group at the University of Washington, included in Workshop Physics, Module 4. In this lab you are going to explore how charge flows in wires and bulbs when energy is provided by a battery. You will be asked to develop and explain some models that predict how the charge flows. You will also be asked to devise ways to test your models using computer-based current and voltage sensors that measure the rate of flow of electric charge (current) and the potential difference (voltage), respectively, and display these quantities on a computer screen using data collection and analysis software. INVESTIGATION 1: MODELS THAT DESCRIBE CURRENT FLOW What is electric current? As you have seen in Lab 1, the forces between objects that are rubbed in particular ways can be attributed to a property of matter known as charge (static electricity). Most textbooks assert that the electric currents through the wires connected to a battery are charges in motion. How do we know this? Perhaps current is something else—another phenomenon. This question received a great deal of attention from Michael Faraday, a famous earlynineteenth-century scientist. Faraday studied the effects of electricity from animals including electric eels summarized his results in a table like the one shown in Figure 4-1, and concluded that ―electricity, whatever may be its source, is identical in its nature.‖ 1 Physiological effect Magnetic deflection Magnets made Spark Heating power True chemical action Attraction and repulsion Discharge by hot air 1. Voltaic electricity X X X X X X X X 2. Common electricity X X X X X X X X 3. Magneto-electricity X X X X X X X 4. Thermo-electricity X X + + + + 5. Animal electricity X X X + + X Figure 4-1: Faraday’s table. The X’s denote results obtained by Faraday and the +’s denote positive results found later by other investigators. Lab 04 – Batteries and Current
The purpose of the first activity is to compare carriers of the current produced by a battery to the static charges deposited by rubbing materials together. You will observe a demonstration using the following materials: • 2 metal angle irons (approx. 15 cm long) • foil-covered Styrofoam ball on a string (2.5 cm diameter) • 300-V battery pack or power supply • hard rubber (plastic or Teflon © ) rod and fur • glass or acrylic rod and polyester, felt or silk cloth • electroscope • alligator clip leads • Wimshurst or Van de Graaff generator (optional) 1 Faraday, M. ―Identity of Electrocutes Derived from Different Sources,‖ in Experimental Researches in Electricity, Vol. I, Taylor and Francis, London. (Reprinted by Dover Publications, New York, 1965, p. 76). Activity 1-1: Comparing Stuff from a Battery to the Rubbing Stuff 1. The angle irons, ball, and electroscope will be set up as shown in Figure 4-2. Figure 4-2: Apparatus for detecting charge. 2. The metal angle irons will be charged in two or more of the following ways: a. Electrostatic Charging by Rubbing. Stroke one plate with a rubber rod that has been rubbed with the fur. Repeat this several times. Stroke the other plate with the glass rod that has been rubbed with the polyester cloth. b. Charging with a Battery. Connect a wire from the negative terminal of the power supply to one of the angle irons. At the same time connect a wire from the positive terminal to the other plate. Lab 04 – Batteries and Current
Page 1 and 2: Name_______________________________
Page 3: Name_________________________ Date_
Page 7 and 8: Question 1-5: Do the charges genera
Page 9 and 10: Question 1-11: What types of materi
Page 11 and 12: You are now ready to explore models
Page 13 and 14: Look at Figure 4-8b and convince yo
Page 15 and 16: 5. Try any other tests you need to
Page 17 and 18: Activity 2-2: Inventing and Constru
Page 19 and 20: Figure 4-12: Two voltage sensors co
Page 21 and 22: 9. Now connect a voltage and a curr
Page 23 and 24: Question 2-7: When you added the se
Page 25 and 26: Question E3-4: How does this model
Page 27: 3. Name the circuit element represe

pre-lab preparation sheet for lab 4—batteries, bulbs, and current

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