Direct Current Circuits

Transcription

1 Name: Date: PC1143 Physics III Direct Current Circuits 5 Laboratory Worksheet Part A: Single-Loop Circuits R 1 = I 0 = V 1 = R 2 = I 1 = V 2 = R 3 = I 2 = V 3 = R 12 = I 3 = V 12 = R 23 = V 23 = R 123 = V 123 = Data Table 1: Series circuit with resistors #1, #2 and #3. Analysis A-1: Calculate theoretical equivalent resistances of the combinations R 12, R 23 and R 123. Compare the values you calculated with the measured values respectively by calculating their percentage discrepancies. Show your work. Theoretical R 12 = % discrepancy = % Theoretical R 23 = % discrepancy = % Theoretical R 123 = % discrepancy = % Page 1 of 7

2 Direct Current Circuits Laboratory Worksheet Page 2 of 7 Question A-2: In a series circuit, on the basis of the data you recorded in Data Table 2, what are the patterns for how voltages get distributed with unequal resistances? Is there any relationship between the size of the resistance and the size of the resulting voltage? Question A-3: On the basis of your recorded data in Data Table 2, what is the pattern for how current behaves in series circuits? At this point, you should be able to summarize the behaviour of all three quantities resistance, voltage and current in series circuits. R a = I 0 = V a = R b = I a = V b = R c = I b = V c = R abc = I c = V abc = I 4 = Data Table 2: Parallel circuit with resistors a, b and c. Analysis A-2: Calculate theoretical equivalent resistance of the combination R abc. Compare the value you calculated with the measured value by calculating the percentage discrepancy. Show your work. Theoretical R abc = % discrepancy = %

3 Direct Current Circuits Laboratory Worksheet Page 3 of 7 Question A-4: In a parallel circuit, on the basis of the data you recorded in Data Table 3, what are the patterns for how voltages get distributed with unequal resistances? Is there any relationship between the size of the resistance and the size of the resulting voltage? Question A-5: On the basis of your recorded data in Data Table 3, what is the pattern for how current behaves in parallel circuits? At this point, you should be able to summarize the behaviour of all three quantities resistance, voltage and current in parallel circuits. R A = I 0 = V A = R B = I A = V B = R C = I B = V C = R BC = I C = V BC = R ABC = I 4 = V ABC = Data Table 3: Combination circuit with resistors A, B and C. Analysis A-3: Calculate theoretical equivalent resistances of the combinations R BC and R ABC. Compare the values you calculated with the measured values respectively by calculating their percentage discrepancies. Show your work. Theoretical R BC = % discrepancy = % Theoretical R ABC = % discrepancy = %

4 Direct Current Circuits Laboratory Worksheet Page 4 of 7 Question A-6: Do your data recorded in Data Table 4 for the combination circuit follow the same rules as they did in your circuits which were purely series or parallel? If not, state the rules you see in operation. Explain. Part B: Multi-Loop Circuits ε 1 = ε 2 = Resistance (Ω) Sources of emf R 1 I 1 R 2 I 2 R 3 I 3 Data Table 4 Currents (ma) Question B-1: Apply Kirchhoff s rules to the circuit of Figure 6 for the actual values used in the circuit. Three equations in the three currents I 1, I 2 and I 3 will result. Solve the three equations for the values of I 1, I 2 and I 3. I 1 = I 2 = I 3 =

5 Direct Current Circuits Laboratory Worksheet Page 5 of 7 Analysis B-1: Use percentage discrepancy to compare your experimental values for the current with the theoretical values. I 1 : % discrepancy = % I 2 : % discrepancy = % I 3 : % discrepancy = % Analysis B-2: State the equation that relates the currents I 1, I 2 and I 3 in the circuit of Figure 6. Calculate the percentage difference between the experimental values of the two sides of the equation. % difference = % Sources of emf ε 1 = ε 2 = Resistance (Ω) Currents (ma) R 1 I 1 R 2 I 2 R 3 I 3 R 4 I 4 Data Table 5

6 Direct Current Circuits Laboratory Worksheet Page 6 of 7 Question B-2: Apply Kirchhoff s rules to the circuit of Figure 7 for the actual values used in your circuit. Four equations in the four currents I 1, I 2, I 3 and I 4 will result. Solve the four equations for the values of I 1, I 2, I 3 and I 4. I 1 = I 2 = I 3 = I 4 = Analysis B-3: Use percentage discrepancy to compare your experimental values for the current with the theoretical values. I 1 : % discrepancy = % I 2 : % discrepancy = % I 3 : % discrepancy = % I 4 : % discrepancy = %

7 Direct Current Circuits Laboratory Worksheet Page 7 of 7 Analysis B-4: State the equation that relates the currents I 1, I 2, I 3 and I 4 in the circuit of Figure 7. Calculate the percentage difference between the experimental values of the two sides of the equation. % difference = % Question B-3: Are the experimental values of the currents for this part of the experiment generally larger or smaller than the theoretical values expected for the currents? Question B-4: An ideal ammeter has zero resistance. Real ammeters have small but finite resistance. Would ammeter resistance cause an error in the proper direction to account for the direction of your error indicated in Question B-3? State your reasoning. Question B-5: The connecting wires in the experiment are assumed to have no resistance, but in fact have a finite resistance. Would this error be in the proper direction to account for the direction of the error stated in your answer to Question B-3? State your reasoning. 6 Laboratory Report Submit a laboratory report within ONE week after your laboratory session. Important: Before leaving the laboratory, have a demonstrator initial on your data table(s)! Last updated: Monday 2 nd February, :13pm (KHCM)