- Experiment No 5 Resistances In Series And Parallel I In Objectives Describe The Current Voltage Relationships For R 1 (78.54 KiB) Viewed 39 times
II. Resistances in Parallel Resistors are said to be connected in parallel when connected as in Figure 5.2. The voltage drops across all the resistors are the same and equal to the voltage V of the source. However, the current I from the source divides among the resistors such that I= 11 + 12 +13 Figure 5.2 The current through cach resistor is given by Ohm's law I = 1 + 12 + 13 VVV = RR2 R3 + R2 For a current through a single resistance Rp in a circuit, I = 1 1 + + 1 1 R1 R2 R3 where R, is the equivalent resistance of the resistors in parallel. III. EQUIPMENT Battery or power supply Ammeter Voltmeter Single-pole, single-throw (SPST) switch . IV a PROCEDURE 1. Examine the resistors. The colored bands conform to a color code that gives the value of resistor. Designate the smallest resistance as Rs and consecutively larger values as R2, R3, and R4. 2. Compute theoretically various quantities for a given circuit arrangement. The quantities are then determined by actual circuit measurements, and the calculated and experimental results are compared. 3. Set up a series circuit with R., R2, and R3, as in Figure 5.1, with a switch and ammeter in the circuit next to the voltage source. 4. Using the resistor values and the measured voltage, compute (a) the equivalent resistance Rs of the circuit, (b) the current in the circuit, and (c) the voltage drops across each resistor. Show your calculations in Data and Results. 5. Compare the experimentally measured values with the theoretically computed values by finding the percent error.
11. 6. Set up a parallel circuit with Ri, R2, and Ra, as in Figure 5.2, with the ammeter and voltmeter connected as before in Procedure 3. 7. Using the resistor values and the measured voltage, compute (a) the equivalent resistance Rp of the circuit, (b) the current supplied by the source, and (c) the current through each resistor. Show your calculations in Data and Results. 8. Compare the theoretical and experimental values by computing the percent errors. 9. Repeat Procedures 6 through 8 with R2 replaced by Rt. 10. Compute the following and record it in Data and Results. If R1 were connected in series with R2 and R3 in parallel (Figure 5.3): a) What would be the equivalent resistance Rsp of the resistors? b) How much current would be supplied by the source? c) What would be the voltage drop V across R? d) What would be the voltage drop across R2 and R?? e) What would be the voltage drop across all three resistors? Figure 5.3 f) What would be the currents through R2 and R3? 12. Set up the actual circuit and trace the current flow to check the circuit. With the voltmeter and ammeter, measure and record the calculated quantities. R2 DATA AND RESULTS Resistor Values R1 R3 R2 R4 Resistors in Series Source voltage V Equivalent resistance Rs Current I Voltage drops across each resistors v1 V2 V3 Computations:
Experimental Values Percent Error I 11 12 13 vi V2 V3 V1+V2+V3 V across resistors as a group Resistors in Parallel Source voltage V Equivalent resistance Rp Current I Current through resistors 11 12 13 Computations: Experimental Values Percent Error I vi V2 12 13 V3 11+12+13
Procedure 9 Source voltage V Equivalent resistance Rp Current I Current through resistors 11 13 14 Computations: Experimental Values Percent Error VI 11 V3 13 V4 14 Resistors in Series-Parallel Source voltage V Equivalent resistance Rsp Current I Voltage drops Vi V2 V3 Computations:
Experimental Values vi V2 Il 12 13 V3 VI. CONCLUSIONS References: 1. Wilson, J. D., & Hernandez-Hall, C. A. (2015). Physics Laboratory Experiments (Eight ed.). USA: Cengage Learning.