In this experiment you will investigate series and parallel combinations of resistors. You are provided with: • the circuit shown in Fig. 2.1 which includes two resistors X and Y • two extra connecting leads. The resistors are not identical. The circuit shown in Fig. 2.1 has been assembled for you. [Figure 2.1]

1. (a)(i)Close the switch. Measure and record the potential difference V_X across X and the current I_S in the circuit. Open the switch. V_X = V I_S = A[1]
2. (a)(ii)Calculate the resistance R_X, the resistance of resistor X, using the equation: R_X = V_X / I_S R_X = Ω[1]
3. (a)(iii)Suggest why the switch is opened after the readings of potential difference and current are taken.[1]
4. (a)(iv)Disconnect the voltmeter and reconnect it across Y. Close the switch. Measure and record the potential difference V_Y across Y. Open the switch. Calculate the resistance R_Y of Y. V_Y = V R_Y = Ω[1]
5. (b)(i)Complete the circuit diagram in Fig. 2.2 to show the resistors X and Y connected in parallel between W and Z. [Figure 2.2] Draw the voltmeter connected to measure the potential difference V_P across both resistors.[2]
6. (b)(ii)Disconnect the resistors and the voltmeter from the circuit on your bench and rearrange them to make the circuit shown in your circuit diagram in (b)(i). Close the switch. Measure and record the potential difference V_P across the resistors and the total current through the resistors I_P. Open the switch. Calculate the total resistance R_P of the resistors in parallel, using the equation: R_P = V_P / I_P V_P = V I_P = A R_P = Ω[1]
7. (c)(i)Theory suggests that, if the two resistors are arranged in parallel, the total resistance of the resistors R_T is given by: R_T = R_X R_Y / (R_X + R_Y) Use the equation and your values of R_X and R_Y from (a)(ii) and (a)(iv) to calculate R_T. R_T = Ω[1]
8. (c)(ii)Two quantities can be considered to be equal within the limits of experimental accuracy if their values are within 10% of each other. State whether your value of R_P from (b)(ii) can be considered equal to R_T calculated in (c)(i). Support your statement with a calculation. calculation statement[2]

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