Banner 1 h2>13.1 Circuit rules AQA AS Physics C13 DC Circuits Kerboodle Answers : Page No. 216 1.Ans- a the current through each light bulb. 1.0 A, 4.0A b the current from the battery, 5.0A c the power supplied by the battery. 30W 2.Ans- a Sketch the circuit diagram for this circuit. b i the pd across the variable resistor, 2.0V ii the current through the torch bulb. 0.20A 3.Ans- a Sketch the circuit diagram. b The ammeter reads 0.20 A, Calculate i the pd across the 20 Q resistor, 4.0V ii the pd acrossR, 2.0 v iii the resistance of R. 10 Ω 4.Ans- a the pd across the torch bulb, 3.6V b the resistance of the torch bulb. 30 Ω

13.2 More about resistance AQA AS Physics C13 DC Circuits Kerboodle Answers : Page No. 219

1. a 16 Ω b 3.0 Ω c 4 Ω 2. . a the combined resistance of the 3 resistor and a 6 Q resistor in parallel 2 Ω b the total resistance Of the circuit 6 Ω c the battery current 1.0 Ω d the power supplied to the 4 Q resistor. 4. 0 Ω 3. a the total resistance of the circuit 3.6 Ω b the battery current 0.83 A c the power supplied to each resistor 2 Ω: 0.5 W, 4 Ω: 1.0W, 9 Ω: 1.0 W d the power supplied bg the battery, 2.5 W 4. a 14.4 W b 2.4 Ω

13.3 Electromotive force and internal resistance AQA AS Physics C13 DC Circuits Kerboodle Answers  : Page No. 222

1. a the total resistance Of the circuit 6.0 Ω b the current through the battery 2.0A c the lost pd 3.0V d the pd across the cell terminals. 9.0V 2. a the current 0.5A b the terminal pd 1.25 v c the power delivered to the 2.5 Q resistor 0.63W d the power wasted in the cell. 0.13W 3.a the internal resistance of the cell 2.0 Ω b the cell’s em f. 1.5V 4.12V, 2 Ω

13.4 More circuit calculations AQA AS Physics C13 DC Circuits Kerboodle Answers : Page No. 225

1. a the total resistance of the circuit 12.0 Ω b the cell current 0.25A c the current and pd for each resistor.

4 Ω: 0.25A, 1.0V, 24 Ω: 0.08A, 2.0V; 12 Ω: 0.17 A, 2.0 V 2 .a the total resistance of the circuit 20.0 Ω b the cell Current 1.05A c the current and pd across the 15 Q resistor. 1.05A, 15.8V 3.i the power delivered to each external resistor, 2.0W ii the power wasted due to internal resistance. 2.0W 13.5 The potential divider

AQA AS Physics C13 DC Circuits Kerboodle Answers  : Page No. 227

1.The brightness of the light bulb increases gradually from zero to maximum brightness. 2.i the current, 0.5A ii the pd across each resistor. 8.0 Ω n: 4.0V; 4. Ω: 2.0V b.i 20 C, 3.0V ii 10C C. 4.0V 3. 2.8V ii 6.4k Ω Banner 8

Practice questions: Page No. 228-229

1.(a) Draw the arrangement, using all three resistors, which will give the largest resistance (b) R = 3.0 + 4.0 + 6.0 = 13 Ω (c) Draw the arrangement using all three resist off, which will give the smallest resistance. (d) 2. (a). (b) 3. (a) (b) c (i) (ii) total power P = I2 R = 2.42 × 11 = 63 W 4. (a) b (i) (ii) (iii) Calculate the resistance of R. (iv) Calculate the emf of the battery. (6 marks) AQA. 2007 5. (i) the total Current in the circuit, (ii) the voltage between the points P and O, pd across PQ = pd across total external resistance = I R = 0.194 × 60 = 11.6 V (iii) the power dissipated in resistor A. Power P = I2 R = 0.1942 × 30 = 1.13 W (iv) Energy dissipated = Pt = 1.13 × 20 = 23 J 6. (a) (i) zero (0 V), or negligibly small (ii) (iii) (b) So that the current supplied by the unit is restricted to a value below danger level.

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