Series and parallel circuitsIB MYP Physics: Subtopic test

1. 1
   A student builds a circuit for a model greenhouse. A 6.0 V cell is connected in series with two resistors, one of 4.0 Ω and one of 8.0 Ω. The cell has negligible internal resistance.

   (a)

   What is the total resistance of the two resistors?

   [1 mark]

   • A12 Ω
   • B2.7 Ω
   • C32 Ω
   • D4.0 Ω

   (b)

   What is the current through the 8.0 Ω resistor?

   [1 mark]

   • A0.75 A
   • B1.5 A
   • C0.25 A
   • D0.50 A

   (c)

   Calculate the potential difference across the 8.0 Ω resistor.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An electrician connects two lamps in parallel across a 12 V supply. One lamp has a resistance of 6.0 Ω and the other has a resistance of 12 Ω. The supply has negligible internal resistance.

   (a)

   What is the potential difference across the 12 Ω lamp?

   [1 mark]

   • A6.0 V
   • B12 V
   • C4.0 V
   • D18 V

   (b)

   Which value could be the total resistance of the two lamps in parallel?

   [1 mark]

   • A18 Ω
   • B9.0 Ω
   • C4.0 Ω
   • D12 Ω

   (c)

   Calculate the total current drawn from the supply.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A group of students investigates how the way lamps are connected affects their brightness. They use three identical lamps and a 4.5 V supply. They connect the lamps first in series and then in parallel, and use an ammeter and a voltmeter to take readings in each arrangement.

   (a)

   Identify the independent variable, the dependent variable and one control variable.

   [3 marks]

   (b)

   In series, the supply current was 0.10 A and each lamp had 1.5 V across it. In parallel, the supply current was 0.90 A and each lamp had 4.5 V across it. Describe the pattern in the potential differences, calculate the total resistance of each arrangement, and explain why the lamps are brighter in parallel.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A new apartment block is being wired. The electrician connects every lamp in each flat to the mains supply in parallel. Later, residents in one flat plug a television, a kettle, a heater and a games console into a single multiway adaptor to avoid paying for extra sockets.

   (a)

   Explain why the lamps in a flat are wired in parallel rather than in series.

   [6 marks]

   (b)

   Evaluate whether the residents should use one multiway adaptor for all four appliances.

   [6 marks]

   Total for question 4: 12 marks

End of questions