Resistance
Q1.
The current in a circuit depends on the potential difference (p.d.) provided by the cells and the total resistance of the circuit.
(a)     Using the correct circuit symbols, draw a diagram to show how you would connect 1.5 V cells together to give a p.d. of 6 V.
(2)
(b)     Figure 1 shows a circuit containing an 18 V battery.
Two resistors, X and Y, are connected in series.
•         X has a resistance of 3 Ω.
•         There is a current of 2 A in X.
Figure 1
 
(i)      Calculate the p.d. across X.
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P.d. across X = ______________________ V
(2)
(ii)     Calculate the p.d. across Y.
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P.d. across Y = ______________________ V
(2)
(iii)    Calculate the total resistance of X and Y.
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Total resistance of X and Y = ______________________ Ω
(2)
(c)     Figure 2 shows a transformer.
Figure 2
 
(i)      An 18 V battery could not be used as the input of a transformer.
Explain why.
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(2)
(ii)     The transformer is 100% efficient.
Calculate the output current for the transformer shown in Figure 2.
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Output current = ______________________ A
(2)
(Total 12 marks)