Series and parallel circuitsIB MYP Sciences: Subtopic test

1. 1
   A student in Mumbai builds a series circuit containing a 9.0 V battery and two lamps, X and Y. An ammeter next to the battery reads 0.30 A, and a voltmeter connected across lamp X reads 3.5 V.

   (a)

   What is the current through lamp Y?

   [1 mark]

   • A0.15 A, because the current is shared between the lamps
   • B0.60 A, because the currents add
   • C0 A, because lamp X uses up the current
   • D0.30 A, because the current is the same everywhere in a series circuit

   (b)

   What is the potential difference across lamp Y?

   [1 mark]

   • A5.5 V
   • B3.5 V
   • C9.0 V
   • D12.5 V

   (c)

   Calculate the resistance of lamp X.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student in Lima is drawing a circuit diagram for a model house. Two identical lamps are connected in parallel to a 12 V battery, and a switch controls both lamps. An ammeter in the wire next to the battery reads 1.0 A.

   (a)

   Which circuit symbol would represent each lamp in the circuit diagram?

   [1 mark]

   • AA circle containing the letter A
   • BA plain rectangle
   • CA circle containing a cross
   • DTwo parallel lines, one long and one short

   (b)

   What is the potential difference across each lamp?

   [1 mark]

   • A6.0 V
   • B12 V
   • C24 V
   • D1.0 V

   (c)

   Calculate the current through one of the lamps.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A technician in Cairo has a 12 V supply, a 4.0 Ω resistor and an 8.0 Ω resistor.

   (a)

   The two resistors are connected in series to the supply. Calculate the current in the circuit and the potential difference across the 8.0 Ω resistor.

   [3 marks]

   (b)

   The technician now connects the same two resistors in parallel across the 12 V supply. Calculate the current through each resistor and the total current from the supply, and state how the total resistance compares with 4.0 Ω.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A school in Accra is decorating its hall for a festival with a string of 50 small lamps. A student, Kofi, tests two ways of wiring three identical lamps to the same battery. He predicts: 'Lamps in parallel will be brighter than lamps in series, because each lamp in parallel gets the full potential difference of the battery.' By eye, the three lamps in series were equally dim and the three lamps in parallel were equally bright. When he unscrewed one lamp, the other two went out in the series circuit but stayed lit in the parallel circuit.

   (a)

   Evaluate Kofi's prediction and his method.

   [6 marks]

   (b)

   Discuss the social, economic and environmental implications of the school choosing series wiring or parallel wiring for its string of 50 lamps, and justify a recommendation.

   [6 marks]

   Total for question 4: 12 marks

End of questions