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4.3 Electric circuits

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Question 4

A student designs an experiment to determine the resistance of an unknown fixed resistor, RRR.

a.

State how the ammeter and the voltmeter must be connected in the circuit relative to the resistor RRR to allow the student to measure the current through RRR and the potential difference across it.

[2]
b.

Describe the steps the student should take to obtain a highly reliable value for the resistance of RRR using a variable resistor in their circuit.

[3]
c.

A circuit consists of a power supply and a single 30 Ω30\ \Omega30 Ω resistor. The current in the circuit is measured to be 0.4 A0.4\text{ A}0.4 A.

A second 30 Ω30\ \Omega30 Ω resistor is then connected in parallel with the first resistor. State and explain the effect of this change on:

  • the total resistance of the circuit,
  • the total current drawn from the power supply.
[4]
Markscheme

4.3 Electric circuits Questions

  1. IGCSE
  2. /Physics
  3. /4.3 Electric circuits

136 exam-style questions on CIE IGCSE Physics 4.3 Electric circuits, covering 4.3.1a Circuit diagrams and circuit components, 4.3.2a Series circuits, 4.3.2b Parallel circuits, 4.3.2c Current and potential difference in circuits, 4.3.2d Combined resistance of resistors in parallel, and 4.3.3 Action and use of circuit components. Each one has a worked solution and a mark scheme showing where the marks go.

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