s Content Connections Circuitry Part 1: Ohm's Law In this activity you will use the data collected from a simple circuit consisting of a variable power supply. an ammeter. a voltmeter. plus a resistor to prove the famous equation of V=1R . Examine the schematic diagram to the right, noting the arrow used to represent a variable power supply, as rar resistor well as the placements of both the v ana_ble @ voltmeter and ammeter: PrwE supply Data: In this experiment, the following was performed: # The above circuit was set up with a resistor of known resistance R = 5.6 Q. # The variable power supply was adjusted to produce 6 different voltages and currents, as read off the multimeters shown in the schematic. Each current and voltage reading was recorded in the data table below. # Note that all currents were recorded in milli-amperes, so be sure to convert all current readings (1000 mA = 1 A). A separate column is provided to add these converted values. Current / (mA) Voltage V' (V) * Content Connections Analysis: 1. b On a separate piece of graph paper. plot a graph of Voltage (y-axis) vs. Current (x-axis) in the appropriate way. Use a ruler to draw a best-fit line through the points. Determine the slope of your line and state the equation of your graph as a relationship between Voltage " and Current /. Show all work below. Slope: Equation: Perform a % error calculation below to compare this slope with the resistor's stated resistance, as listed in the Data section. % error = = Questions: L 2. Was Ohm's Law confirmed in this activity? Explain how you know. From your graph equation, extrapolate values for the following (show work): a) Current= 1.4 x 10 mA; voltage =7 b} Voltage = 9.5 V: current =7 Describe how the slope of your graph would appear (more steep or less steep) if the resistance used in this activity was: a) larger: b) smaller: A filament light bulb acts as a resistor in any circuit, with the difference that it initially heats up and increases its resistance when it is first turned on. Describe how the shape of your line, as well as its slope, would be affected if a light bulb was used in this way in place of the resistor. o Content Connections i'art 2: Internal Resistance In this activity you will use another set of data collected from a different simple circuit consisting of a single 6-volt battery, an ammeter, a voltmeter. plus a variable resistor that behaves much like a household dimmer switch. In this case the data will be used to determine both the EMF and the internal resistance of the battery. Examine the schematic diagram below, noting the arrangement of the battery o and variable resistor as well as the placements of both the voltmeter and ammeter: 0 variable resistor R Data: In this experiment, the following was performed: # The above circuit was set up with a 6-Volt battery: The variable resistor was adjusted to produce 6 different voltages and currents, as read off the multimeters shown in the schematic. Each current and voltage reading was recorded in the data table below. # Note that all currents were recorded in milli-amperes, so be sure to convert all current readings (1000 mA = | A). A separate column is provided to add these converted values. Current [ (mA) Voltage V' (V) 1050 5.4 310 6.2 1995 4.5 495 6.0 3485 3.2 1510 5.0 o Content Connections Anal}'sis: 1. On another piece of graph paper, plot a graph of Voltage (y-axis) vs. Current (x-axis) in the appropriate way. Use a ruler to draw a best-fit line through the points. 2. Determine the slope of your line and state the equation of your graph as a relationship between Voltage 1" and Current /. Show all work below. Slope: Equation: 3. Determine the EMF and the internal resistance of the 6-Volt battery used in the activity in the following way: Re-arrange your equation from the graph to the form of y = b + kx; # Compare this equation with the known formula: F'r= - Ir. EME: Internal resistance: Questions: 1. Describe how the slope of your graph would be affected if: a) the internal resistance was greater. b} the EMF of the battery was smaller. 2. Explain why a battery with a large internal resistance would not be very useful as a power source. Content Connections Conclusion: In a paragraph or two on a separate page, describe what you learned in the two parts of this activity. The following should be included: # Was Ohm's Law proven in Part 17 Use evidence to support your answer; # What information was determined by performing the experiment in Part 27 Explain why this information is useful; # What sources of error could occur in performing each experiment (which you didn't do) and analyzing the information (which you did do). Explain what could be done to reduce these inaccuracies. Once completed, be sure to include the conclusion as well as the two graphs in your submission