> Objective: Verify the relation between electric current, electromotive force and resistance. > Equipment and Materials: 12 V AC/DC Power Supply Resistor Box Conductors (wires) Ammeter Voltmeter *Theory The electric current is directly proportional to the electromotive force of the battery (also called electric potential or voltage) and inversely proportional to the resistance of the resistors connected as part of the circuit. The resistance of the wire depends on several factors like the resistivity of the material used for the wire, the cross sectional area of the wire and the length of the wire. PL R= A There are components of the circuit, like light bulbs or others, which are call resistors because their functioning implies to offer resistance to the flow of current through the circuit. > Procedure Experiment 1: Variation of current with voltage when the resistance is constant (DC circuit). Set up the electric circuit shown in Figure 1. (connect the wire to the 0.05 A port of the ammeter, so 1.0 A read in the scale is actually 0.01 A] 2. Set the resistance equal to 800 0 Complete the Table 1, emf vs. current 4 Construct a graph, using Microsoft Excel, of Emf (x - axis) vs. Current (y - axis), based on the date in table 1. 5. Find the line (show its equation) that better fit the points plotted. . Determine the slope of the line.7. If slope = = find the experimental value of the resistance of the circuit. 8. Find the Percent of Error between the experimental and the theoretical value of the resistance using the formula: % Error = Rtheoretical - Rexperimental - x 100% Rtheoretical B emi D Figure 1. Electric circuit Resistance, R - 800 0 Emf, V (V) Current, I (A) 2 Table 1. Emf vs. Current Experiment 2: Variation of current with resistance when the electromotive force is constant [DC circuit). 1. Set up the electric circuit shown in Figure 1. (connect the wire to the 0.05 A port of the ammeter, so 1.0 A read in the scale is actually 0.01 A) 2. Set the emf equal to 2 volts . Complete the Table 2, resistance vs. current 4. Construct a graph, using Microsoft Excel, of 1/resistance (x - axis] vs. current (y - axis), based on the data in table 2. 5. Find the line (show its equation) that better fit the points plotted. 6. Determine the slope of the line. 7. If slope = V, find the experimental value of the resistance of the circuit.8. Find the Percent of Error between the experimental and the theoretical value of the resistance using the formula: % Error = Rtheoretical - Rexperimental x 100% Rtheoretical Electromotive force, V = 2 V Resistance, R (Q) 1/R (1/0) Current, I (A) 200 1/200 300 1/300 400 1/400 500 1/500 Table 2. Resistance vs. Current > Conclusions Write the conclusions of your report based on the results obtained after performing the experiments (how the current change with the change of the voltage and the change of the resistance; percentages of errors obtained, etc.)