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IGCSE · 4 · multiple choice

Electricity and magnetism · Question 3

Electricity and magnetism · Original GioPhysics question with a detailed, mark-by-mark answer guide.

Demand
routine
Marks
1
Topics
1
Answer
Complete
A 6.0 ohm resistor and a 3.0 ohm resistor connected in parallel6.0 Ω3.0 Ω
Fig. 3.1A circuit diagram of two resistors connected side by side between the same pair of points. A wire arrives from the left and reaches a junction, marked with a dot, where it divides into two branches. The upper branch contains a resistor labelled 6.0 ohm and the lower branch a resistor labelled 3.0 ohm. The two branches rejoin at a second junction dot on the right, from which a single wire continues away to the right.
multiple choice1 mark

Two resistors of 6.0 Ω and 3.0 Ω are connected in parallel. What is their combined resistance?

  1. A

    0.50 Ω

  2. B

    2.0 Ω

  3. C

    4.5 Ω

  4. D

    9.0 Ω

Ready to self-mark?Reveal the detailed answer guide
Answer overviewCorrect answer: B — 2.0 Ω
01

Answer and reasoning

1 mark
How to approach it

Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.

  1. 1

    The correct choice is B: 2.0 Ω

  2. 2

    D is the series total and C is the mean — both offered to candidates who reach for an average. A stops at 1/R without inverting. Any parallel answer must be smaller than the smaller resistor, which rules out C and D at a glance.

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