Circuits - Series and Parallel
Q4.
(a) A student is given three resistors of resistance 3.0
, 4.0
and 6.0
respectively.
(i) Draw the arrangement, using all three resistors, which will give the largest resistance.

(ii) Calculate the resistance of the arrangement you have drawn.

R = 3.0 + 4.0 + 6.0 = 13

(iii) Draw the arrangement, using all three resistors, which will give the smallest resistance.

(iv) Calculate the resistance of the arrangement you have drawn.

1/R = 1/3.0 + 1/4.0 + 1/6.0 = (4.0 + 3.0 + 2.0)/12 = 9.0/12 = 0.75 
R = 1/0.75 = 1.3

(5)
(b) The three resistors are now connected to a battery that provides a potential difference of 12V, as shown in the diagram below.

(i) Calculate the total resistance in the circuit.

1/R = 1/3.0 + 1/6.0 = 1/2.0
Rparallel = 2.0


RTotal = 2.0 + 4.0 = 6.0

(ii) Calculate the voltage across the 6.0
resistor.
(4)
(Total 9 marks)