CAIE A-Level Physics AS 9.3 Resistance and Resistivity Questions

Practise using V/I and V = IR, interpreting I–V curves, calculating resistivity and explaining temperature-dependent sensors and conductors.

Exam points

define and calculate resistance using V/I and V = IR, and test proportionality for Ohmic behaviour
interpret I–V characteristics of metallic conductors, diodes and filament lamps, including changing resistance
calculate resistance or resistivity with R = ρL/A and relate geometry and material to resistance
explain temperature-dependent resistance in filament lamps, LDRs and negative-temperature-coefficient thermistors

Covered syllabus points

9.3.1—Resistance 9.3.2—V = IR 9.3.3—The I–V characteristics of a metallic conductor at constant temperature, a 9.3.4—That the resistance of a filament lamp increases 9.3.5—Ohm’s law 9.3.6—R = ρL / A 9.3.7—The resistance of a light-dependent resistor (LDR) decreases 9.3.8—The resistance of a thermistor decreases as the temperature increases (it

[Maximum number: 1]

Which equation is used to define resistance?

energy $=(\text { current })^{2} \times$ resistance × time

potential difference = current × resistance

power $=(\text { current })^{2} \times$ resistance

resistivity = resistance × area ÷ length

[Maximum number: 1]

A voltmeter connected across a resistor in a circuit reads 3.6 V .
What could be the current in the resistor and the resistance of the resistor?

current

resistance

150 mA

$0.24 \mathrm{k} \Omega$

15 mA

$2.4 \mathrm{k} \Omega$

1.5 mA

$0.24 \mathrm{M} \Omega$

$15 \mu \mathrm{~A}$

$240 \mathrm{k} \Omega$

[Maximum number: 1]

The I-V characteristics for four components, A, B, C and D, are shown.
Which component has the greatest resistance when the potential difference across it is $V_{1}$ ?

Figure for Question 3 — CAIE A-Level Physics AS

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Covered syllabus points

Question 1

Question 2

Question 3